I`ve had good success heating the area with a propane torch,you MUST hold it in the correct position untill cool. Fixed quite a few glass parts this way.
You may have to repair the gel-coat afterwards tho.

70` Cuda`,440 6BBL Jerico,Dana 4.56 Still on 93 Pump Gas
9.87 @ 136/1.31-60ft.`09 Mopar Nationals PASSON PERFORMANCE "Stick-Shift" Champ!
2013 StickShift Challenge Winner@ Mopar Nationals!