I've got a 96 xj 2 door and I understand its easy fix sagging headliners on xj's. my question is, do I need to buy new material, or can I just carefully peel it off, then remove the old foam stuff, then glue the fabric back on. Will the fabric get too stretched out?

 

You could try it but I don't think you'll be happy IF you manage it.
Best to replace with new headliner material. Big fabric stores like JoAnn's carries it in several colors. Use spray adhesive that is specifically for headliner and buy 2 cans. The general purpose stuff won't last. I did my headliner, sunvisors and roof console and all looks like factory new.
Good luck.

 

Sorry man, but when you initially take the fabric off, it will get ruined. The headliner "fabric" is acually made up of two different materials attached together. The part that is on the outside is this thin fabric material. It is backed by about 3/16" of some sort of flexible foam. When you go to remove the material, the foam sticks to the headliner board itself and needs to be brushed off. Sorry, hard to explain. I picked up some headliner specific material from Pepboys that looks brand new and has the same look/feel as the original material.

Beast of luck,
Taylor

 

I wound up bedlining it. I did it a few months ago, I took the whole headliner board out, lots of work to even get to the point of sliding it out.. It's all done now! Pictures on my profile!