Re doing shower tile. Must you remove and start over w/ new sheetrock?

I’m about to do mine. Most of my white tile is in good shape so I plan on removing just the loose, broken ones and make a pattern with some penny tile in a yellow I bought. If you’re going to replace all the tile then yes, you should take off the old tile and adhesive down to the backerboard. If you just put it on top of the old, the new tile would have nothing to sink it’s teeth into. Peel and stick can go on top of the old tile If the old tile is otherwise in good shape. You can also paint your tile.

As long as your water proof Sheetrock is in good condition or someone didn’t cheat and use regular Sheetrock in a shower area as I have found on jobs from time to time! You can reuse your existing sheetrock as long as your surface is scraped or sanded lightly where it’s smooth to reapply your tile. If sanding be sure to wipe off any loose dust before applying tile!

it depends on what sheetrock was used. https://www.thespruce.com/tiling-a-shower-1821373

Yes

It's been my experience that once you remove the old tile, the backing sheet rock isn't in good enough shape to be reused. I've also seen that trying to tile over old tile just never works; the new tile doesn't have anything to grab on to, it provides an oddly deep layer on the wall, etc. If you're really planning on putting peel and stick over the tile, good luck, because not only will it look cheap, but it might not hold up in the humidity. I moved into a house with peel and stick tile on the floor in the bathroom (a quick fix to make it presentable for selling) , and it didn't last long. It's really just best to do it right, and it will last for years.

Since your tile is in good shape also, I think it’d Be good to do like I am, remove just some of the tile and maybe use a different color or maybe mosaic, or even paint, or a combination of all 3 lol. They make real good tile paint now that would be excellent for a shower wall. From what I’ve read, and I’ve been reading a lot in preparation for my tile job, for best results if you aren’t going to paint, then remove the tiles. However, they do make tile panels you can install over tile, because they’re Thin and not real tile. Good luck with yours. We probably will wait a little while to do ours- we have a lot going on right now( in other words, we have to quit procrastinating!)