Old lithop leaves are suppose to slowly shrivel and totally dry out, while new pair is supposed to grow from the center (that is very very basic outline of how they behave...).
When doing your research - did you read info about their growing conditions?
Too much water usually kills them.
Difficult to judge from your photo, but center (right between the old leaves) looks dark - maybe I am just seeing things - if so, it may be damaged.
Is it possible to get really good close-up?
It would be helpful to post where you are located - zone and/or general location besides your name is very helpful.

Thank you, Rina!

I'm based in the UK, it is summer here, but still a wet region.

I repotted it last month, the root might have been damaged by that, so I wanted to water a little (starting 10 days after repotting) to get the root to establish itself a bit.

I water very little as compared to before. I read that in the summer rest period some people do water although very little, just to stop the leaves from looking shrivelled. But now I'm thinking it is shrivelling is from 1) either the inside leaveas having grown a little, or 2) from damaged roots, plus a little sunburn perhaps

The small growth is very dark indeed... I hope this picture is a bit better.

Would you suggest to stop watering at all for a few weeks?

My entry is not totally related with your topic but i just wanted to add this information.

One of my friend (He's been in Lithops for a long time) told me that "The roots need to be cut before repotting,if you dont cut, the plant can die." So i did what he said. I cut the roots and waited around 2-3 weeks for new roots to appear.

Here is the pic :

Not the op but...Thank you so much for the info Rina! I had no idea they should not grow in gritty mix. Will be changing asap!

@fatich - thanks for sharing this, did you mean you cut the root, you leave it outside of a pot/soil and then you plant it? Btw, I was worried as when I repotted I didn't really see a tap root on mine, it look more like the picture you posted

@rina - thank you again, very useful post. I think I have the right soil. The bits on watering especially when new leaves are forming is interesting

Ca Chu
I am glad you find the links useful - even if I knew as much as those guys, I couldn't say it as well...
And great that you posted your location...Hope your lithop survives and thrives for you, update if you can.
Rina

If you can do this.....

then you can do this....

In grits

I might be wrong but the bit of dead stuff in the center of the first picture looks like the remains of a dead flower.

@Rina - thank you for your help!

@ nomrn nudum - hi, thanks for your post, could you give some tips on msiting? Im not sure how often and how strongly it needs to be done

@ polypompholyx - yes, its last years flower, I tried removing it but it is very toughly connected to something inside and I don't want to damage the small growth by pulling it out

Yes, the old flower leftovers are visible...but the 'inside' looks little too dark - then again, it could be photo.

The new growth should be of color same as plant.

Mine tend to enjoy a late evening mist after sun set I start at the edge of the pot and water one pot at a time. Pot by pot I pump the mister an avg of 7-10 times with a close to even temped water moving the spray toward the heads I usually mist the outer pot and attempt to sort of scrub while towel wiping them dryer for outer pot cleanliness reasons.

I don't have a " watering schedule" per say I tend to water them more often when warmer. My logic being. If I sat on on the upper board that long day after day I'd be needing more water per hour than they'll get in a eight week time frame

Second logic being....In the lands of Lithops where warmer days are followed by cooler nights them cooler nights will usually carry moisture in the air.

While outside I water more frequently than not with apx. the same volume of water

An indoor Lithops at the brightest window will be cooler than an outside Lithops, cooler air holds moisture longer than warmer air. For the inside Lithops it would be main reason for watering less frequently. I can't determine watering frequency for the inside Lithops during the summer but would imagine the volume would be consistent. In in colder winters ( mid - late Oct early Nov - March middle) I store them in a brightest window row inside Winter watering here would be (more or less) 100 drops for all four of them as a guess.

nomen_nudum

I am not sure I understand what you mean by ..."with a close to even temped water"...

Is it perhaps warmer (tepid=lukewarm, at room temperature) water you are referring to or something else? I can use any good advice.

Temped water : close to the same air temperature as the room or outside air.

nomen
Thank you - I did google term temped water prior to asking and again now, but temped doesn't come up. I am familiar with terms tepid, tempered...but not temped as relating to water - could you point me in right direction please.

It's commonly used as a verb in aquaculture as well.

Rina you are in the right direction. No pointing needed

@nomen nudum - thank you, I find your misting tips very helpful, I might have given too little water, now that I increased it a little bit through misting, the colour appears slightly darker

@ rina - you have beautiful plants - I see what you mean, the new ones do have the same colour

I have another succulent I have a question about - Its outgrown the pot by quite some time, I recently read plants die if pots are too small. would you repot now or wait til next spring (its summer time here)

Uncertain toward the 'ideal' time to re-pot these & pup splitting possibilities as well.

I'd enjoy the flowering then consider re-potting ASAP. Would add a few drainage holes on the bottom by use of nails if no drainage

Thank you! I was sold the plant like that and will defintiely get a better pot allowing drainage :-)

I would wait til spring to repot the plant. I am not sure if it's personal taste or what.

Definitely needs drainage if it doesn't have it. But it's flowered in that so it can't be too unhappy.

Thanks, Laticauda - yes, it's actually been in this pot for two years and flowers all the time. The pups have grown plenty this year and the main plant is starting to ben over. I'm wondering if spring is too long to wait with all this growth this year...

If the top is getting out of control, I'm sure you could cut it back to a more manageable size and root the top you cut off.

Is it still actively growing? Do you think you'll put it in something bigger or just take the pups off the mother plant and keep her in the old wash tub?

Good questions, I think I'll defintely repot the mother plant, maybe together with most of the pups. I want them to grow out of the pot downwards, I've seen a nice picture of a plant I'm kind of imitating. I was going to repot one of the pups for a friend.

Cutting back the top seems interesting, I didn't think of that before :-)

What did you decide to do?