Well, not sure what yours is like or how you can take it down to repair, but if the edges are easy to get loose you can get some 3M spray adhesive (they make a "normal" one and a "super adhesive") that would stick it back up. You'd have to be careful with wrinkles and overspray, and the foam would have to be in decent shape (some foam deteriorates after aging and just falls apart...so nothing would stick to it) 3M Hi-Tack 76 or 3M Super 77 would be two choices. You can get these at a lot of auto parts stores.