Other variables to consider are how far we are from the money, and whether the raises is a serial raiser who has already shown that he can fold. If he is a dead tight rock, then chances are your QQ/JJ may already be dead.
There is little point calling here and seeing what happens on the flop.... say the flop comes 10 hi and you have JJ.... original raises bets an amount which if you call would commit you, therefore it"s now all or nothing. Do you fold? If so, what flop were you hoping for? If the board comes with over cards, and he bets, you have little room to play - all in or fold. If he checks and you bet, you are probably going to end up committing yourself to the pot.....
..... so, back to preflop, given all the scenarios above, I"m re-raising all in and hoping to get away with a small take down.... or to be ahead of a lower pair or AK.
This would all change if I was a stacked a little more deeply than just plain "medium". If I have sufficient chips to be able to raise/fold after the flop, then I"m flat calling preflop and going for a ride on the flop.