You need to create a deep enough area for the grout to adhere. You don’t want to use sandpaper, you want to take out the old grout. A tile blade in an oscillating saw would be the fastest, though the pointy end of a painters five in one tool will give you a better workout.

I bought several grout removal tools when I regrouped my bathroom. One of them was that narrow. You do need to remove most of the grout, maybe not all.

Good opportunity to upgrade. Even a smooth laminate would be an upgrade to tile counters with grout.

That is a beautiful tile job with a marine edge and undermounted sink. Laminate is not an upgrade, and neither is granite.

Once you get modern grout in there it will be better than ever. But I do not envy you the job of removing the old grout. :)

@HALLETT & Co. The tile blade in the oscillating saw is appealing, but I'm afraid that it's requires much more experience and a steadier hand than what I have. I have a Dremel that I was about to use on the grout until I realized I wouldn't be able to reach the grout at an angle. It was very intimidating holding a tool like that so close to the tile. 

I'm going to look for the painters five in one tool now.

Thank you Seabornman, Hu, and Fori for the feedback. I would love to update this whole kitchen, but it's not in my budget right now. Also would have loved to change only the countertops and the sink but I'm reading that one might as well remodel the whole thing if going that route.

That depends upon the condition of your cabinets. If they are still in great shape, it may be beneficial to change countertops, and sink. If you like your tile stick with it. . If you are reading here, that seems to be standard gut the whole thing, but, many times, that really isnt necessary. Everyone wants to improve their kitchen, but, sometimes it can be done and done well on a limited budget. Not everyone has 50,000 to spend on a kitchen. Sometimes, existing cabinets are also much better quality, than some of the junk, that is on the market these days.

Paying other people for labor is where "worth it " tends to go out the window. Labor is such a large part of a project total that the materials cost is small in comparison. When laminate counters are $2500 installed, and Solid Surface is $2700 installed, and Granite is $3000 installed, it's easy to creep up to that $3000. But when you compare it to DIY laminate maybe being $300 if you DIY the fabrication, then $3000 is much less justified for 50 year old cabinets. $300 and sweat equity is probably "worth it" for those 50 year old cabinets though.

Update: I was able to remove the grout with some very fine tools. Some parts were easier to remove than others. Hopefully there's enough surface area for the new grout to adhere to!

UPDATE: Hi Houzz Fam, I made a HUGE rookie mistake. Can you guess what's wrong with this picture? (It's not the painter's tape)

Did the grout dry on the tile? I’m no pro, so just guessing!

Looks like you didnt wipe the grout off the tiles, and now you have a mess.

Good guesses! I accidentally used SANDED grout in my tiny 1/16" joints on my kitchen counter! I noticed the mistake right after grouting the whole area and was able to remove the wet grout easily with water. After painstakingly chipping away the dry grout for hours, removing wet grout was a breeze. Just another delay in my DIY project, of course.

Were you just saying you managed to clean all that? Must have taken a lot of elbow grease if you did, since dried on grout is horrible to remove. LOL

@cat_ky haha when I realized my mistake, the grout was still wet. It actually came off easily with water

Yay!!!! If you havent had to remove dryed grout on tile, then you are one very lucky person. LOL

It looks great!

Beautiful job!!!!!! And beautiful tile job, too! Glad you were able to restore it.

You put a lot of work into this project and the result is fantastic!! I'm increasingly falling back in love with tile counters like this.

wow,wow,wow, it looks wonderful

Nice! Please come do my 1950s bathroom. I will pay you! 😁