Make your decision before the flop. If you don't think he needs aces do do this, then push perflop (dont let a scary ace come and you fold to a QQ cont bet). However, reraising huge out of position is almost always aces, at least in my experiance at 2/4 party. It's always tough to fold kings preflop, but a blind reraise is a spot I can usually get away from.
Actually, I'm curious to see what others say, as I'm often in this spot myself and feel like a fold is too weak. How do other people play kings when someone else (who you dont have much of a read on) is representing aces, and your sitting there with 100 BB?