Leanne Ford of HGTV fame does a lot of white washing of brick with a special mortar mix that she has pioneered herself. The average person would use something more like Romabio limewash which comes in several colors, although I have seen reviews of it that it doesn't always stick to the brick well and can come off if you touch it. Technique with all these products is important. You put it on then selectively remove some of it. You can learn more about it by researching the German Schmear technique. Yes, regrouting can be done. It is called repointing and is expensive to hire done and also messy because current grout must be removed for this to work. A more common treatment for aging fireplaces these days is to simply select a tile, marble or travertine that you like and surface over it. It can create an entirely new feel to the home and be very well worth the effort. Sounds like you're not considering that at the moment, but given that your other options are fairly labor-intensive and/or expensive I think that I resurfacing should also be on the table for you given that the cost is roughly equivalent.

I wouldn’t change the color of it. It’s beautiful and organic. I think it looks great with your house — it adds warmth and character, and repeats the look of your wonderful flagstone outside.

Hopefully you can find someone local who can clean her up and repair anything.

(I am so, so tired of whitewashed brick and stone I could scream ... but I’m an outlier here for sure!)

Does anyone know if it is standard with flagstone to have such large grouted gaps? Doing something new with this grout is going to be challenging considering how much there is of it. I agree with the poster that said too much whitewashing and eliminating of original brick effect seems to be done these days. I furthermore cringe when I see people paint brick an opaque color. That said, I've seen some beautiful renewals with resurfacing using an entirely new material on top. Jessica Alba gave a tour of her new home recently for Architectural Digest. You can find it on YouTube. She redid two fireplaces with marble veneer, and they look lovely and incorporated into the otherwise relaxed and modern tone of the remainder of the decor.

I think the fireplace is very well done. The main problem is the incremental addition of all the clutter that has occurred. If that were my home, I'd remove every single thing on the hearth, the two lamps, and -- though you probably don't want to hear it -- that television. The tv is a distracting focal point and it's very high placement is terrible from an ergonomic standpoint. Yes, people put tv sets above the mantel all the time, but that doesn't make it a good idea either from a practical or a design standpoint. The placement of a tv for viewing comfort should be approximately at a height where the midpoint of the screen is at eye level or a little higher when you are seated; yours is probably 5' higher than it should be.

The only thing I would do to that fireplace is paint the mantel -- maybe a semi-gloss black -- and then consider putting one, nice vase on it.

You could have it regrouted with a lighter grout, that would really lighten it up. Like this https://www.pinterest.com/pin/240520436338627485/

I see nothing wrong with painting bricks, as I hate bricks, but I would not paint stone. Bricks are ugly and depressing (to me) to begin with, but stone is a natural product that generally has interesting color variations.

The fireplace does have a "Flintstones" look to it and could be improved by refacing it with another material, such as marble, as noted above. I would consider covering it with some material that could be painted, such as plaster. I prefer stucco fireplaces to stone ones, but then I prefer no fireplace at all, considering the climate where I live. Brick fireplaces are the worst IMO. I wonder if you could put drywall over it.

The fireplace is gorgeous! You mentioned it's dingy. Have you looked into cleaning the stone? I would start there. And like @Hansen Wholesale suggested, I would remove most of the extra stuff. I do think a fireplace screen would look nice as well.

I would leave the stone. Paint the mantel off-white or cream. Remove the lamps, they look a bit awkward. Maybe add some large decor pieces in place of the small items.

"Up dating" usually means changing something that is classic of the period and trying to make a house look like something it isn't.
Don't mess with that beautiful stone. If it's dirty ,scrub it with a brush and some all purpose cleaner, but good heavens don't paint it or whitewash it or change the grout....
And If you paint the mantle white or off white it will look like a white stripe across that stone.....but I agree on the lamps....and I would reposition the TV. Not a fan of a tv as a mantle ornament.

Thank you!

A light white wash a new white/ off white grout and bulkier white mantel would look great and tie it in to your trim color.