Opp is 40/10/0.6. Bet again on the river or check/call?

Full Tilt Poker
No Limit Holdem Ring game
Blinds: $0.10/$0.25
8 players
Converter

Stack sizes:
Hero: $25.35
UTG+1: $24.25
MP1: $35.40
MP2: $32.35
CO: $21.40
Button: $18.25
SB: $22.30
BB: $22.25

Pre-flop: (8 players) Hero is UTG with A A
Hero raises to $1, 3 folds, CO calls, 3 folds.

Flop: Q K 4 ($2.35, 2 players)
Hero bets $2, CO calls.

Turn: J ($6.35, 2 players)
Hero bets $4, CO calls.

River: 8 ($14.35, 2 players)
Hero ????