In a $5 rebuy people will get it in with draws so often early that I'd try to raise get it in on that flop.  If he has it this time just rebuy, but I think looking to build a stack during the rebuy period is too important to just call and re-eval.  I never want to go broke in a limped pot, but people gamble in rebuys.  It was limped pre so KQ is less likely, and on a board like that I don't think he is check raising as a stone bluff.  He most likely has a draw, and people like to get it in with draws in rebuys, therefore I'd raise.  He could even have something like Q2 and be dominated.  Not sure what the stack sizes are though so hard to say exactly how much I'd raise or whether I'd just jam.