The roof liner is starting to come down right at the rear of the sunroof (the plastic part, not the fabric part.)
I've tried double sided tape and velcro but nothing seems to stop it from coming back down.
Any suggestions on what to try?

 

Ttt

 

I used a lon strip of velcro and glued it to the roof. and then I doubled up on the parts where its lower. Its been hoding up for over a year now and I ride with my sunroof open most of the time.

 

Ask your local service shop what type of adhesive they use for the roof liner. When the liner is not snug usually a rattle with develop, they lathe the adhesive to it and rattle gone. I'm sure it'll fix your issue as well since the effected area is the same.