Annoying spot in WCOOP $215 rebuy, not sure what's best

[AAismyfriend]

EP cold caller is a loose donk. I'm a cash game player, and have limited tournament experience, and just would like to know what you think is best here. I feel like he rarely folds here when i bet, but at the same time c/fing seems weak. thoughts?

PokerStars No-Limit Hold'em Tourney, Big Blind is t50 (9 handed) Hand History converter Courtesy of PokerZion.com

MP2 (t10822)
MP3 (t2625)
CO (t8495)
Button (t10595)
SB (t10825)
Hero (t11090)
UTG (t18203)
UTG+1 (t8215)
MP1 (t5885)

Preflop: Hero is BB with K[[img]/images/graemlins/heart.gif[/img]], A[[img]/images/graemlins/heart.gif[/img]].
[color=Gray]1 fold</font>, UTG+1 calls t50, [color=Gray]2 folds</font>, MP3 calls t50, [color=Red]CO raises to t200</font>, [color=Gray]2 folds</font>, [color=Red]Hero raises to t700</font>, UTG+1 calls t650, MP3 folds, CO folds.

Flop: (t1675) 7[[img]/images/graemlins/diamond.gif[/img]], T[[img]/images/graemlins/spade.gif[/img]], 3[[img]/images/graemlins/club.gif[/img]] [color=Blue](2 players)</font>
[color=Red]Hero ???