Rear VIew mirror problem!

Hi all,
My friend and I took a camping trip for the long weekend, went to hot springs, it was great!
However, while driving home throughthe Central Valley at 102 degrees the rear view mirror came unglued from the windshield!
NOw I want to help reattach it, what kind of glue do people recommend? This is for a 91 dodge caravan, by the way. Also there is still a glue spot onthe windshield, does that need to be removed first? If so, how?

Thanks!