i got some advice from a headliner installer( took it there to see what he would charge and do for my 92 9000T..(which is doing the same)..
1. if you push into your headliner does it leave a dimple? if so then your foam liner underneath is rotted away/deteriated result new headliner needed. if not then you can fix it DIY
2. what he told me was he was going to get a syringe with a needle i guess you can get at auto parts joint or a body shop parts place...
then inject it(little at a time)in the bubble where it's pulling away then smooth it out as you go get the headliner tac glue... squirt inside on to the foam then after it's taccy smooth the fabric back onto it.he didnt say what direction to smooth the fabric back on but I assume back towards the outside og the car..you can ask some local headliner installers if they can do it ...like I sadi as long as your foam is not shot...I have to unfortunatly get the whole thing replaced then buy my new fabric to place over the new headliner(my interior is charcoal grey with black dash and consoles...I'm putting grey background with black G Guuci fabric over the OEM one..then doing the armrests and recovering the front and rear roof supports in the charcoal to match the door trim...that counts for the sunroof as well..all for around $275.00 US plus the cost of the Gucci fabric which I havent found for any less than $45.00 a yard..need 5-6 yards($270.00)..so for a totally new inside it's about $545.00 US.... I hope this helps you avoid my downfall of waiting till the foam shoots craps..