There is a product that I purchased a while back that is really designed to repair broken heating elements in rear window defroster (not the connector to it). It comes in a small bottle (much like fingernail polish) with a brush. It has the appearance of liquid copper. I used it to repair the heating elements in my rear window defroster. Here in Canada, you can get it at Canadian Tire, however in the States, I'm certain you can get it at most any automotive store.
As for the connector to the rear window defroster: you can simply use 5-minute epoxy to reattach it to the glass. Just make sure that when you do reattach it, you get the contact as close to its original position as possible and do not get any epoxy between the connector and the original point of contact with the heating element. Once the epoxy sets, just brush on the liquid copper to bridge the gap between the connector and the heating element.
It works like charm