heated wing mirror coming unstuck

[cnprior]

hello, my drivers wing mirror is flapping as the 'glue' is coming to the end of its life.
what do others use to stick their mirrors on with?
I've thought about unibond glass and mirror glue........but will the heated mirrors still work?

thanks,
Chris
Chris
p.s. car is a 2.0tdi Passat blueline.