Do a search here for this, there's another thread about it.
I used the OTC epoxy that you buy at the local parts store, just make sure it is the type specifically made for this, conductive epoxy. It is good for reattaching the spade and fixing defroster grids. It's been two years, lots of wintertime use of the defroster and no problems with the repair.
Make sure you follow the directions and with a clean working surface it should work well.