2004 1500 Quad Hemi -

So, the mirror fell off and I glued it back up with Permatex. Let it "cure" a day before hanging mirror. In the about mid 90's it fell off again after about 3 days.

My windshield had a little thin foil like piece attached to the windshield where the mirror is supposed to glue up (it's even shaped like the mounting plate/bracket).

Question: Is this foil supposed to be scraped off also? It seemed like it was supposed to stay there. Is there a better adhesive?

Thanks in advance!