AA getting raised on flop, what to do?

[cd1680]

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.25/$0.50
6 players

Stack sizes:
UTG: $49.50
UTG+1: $61.25
CO: $62.65
Button: $46.25
Hero: $94.90
BB: $42.30

Pre-flop: (6 players) Hero is SB with ac as
UTG raises to $1.75, UTG+1 folds, CO calls, Button folds, Hero raises to $7.5, BB folds, UTG calls, CO calls.

Flop: tc 6d 7h ($23, 3 players)
Hero bets $15, UTG raises to $40, CO folds, Hero ????

villain is 39/13/1.03 over 80 hands and i am playing regular solid tight aggressive. what do i do here?