5-bet, 7-bet, or call the river 4-bet?

[spydog]

For those of you that haven't played Crypto sites, you can go as many bets as you want on the river headsup.

Villian is unknown and has plenty of money left. How many should I put in on the river?

Cryptologic 5.00/10.00 Hold'em <font color="#0000FF">(6 handed)</font> link

Preflop: Hero is BB with 9[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/club.gif[/img].
UTG calls, <font color="#666666">2 folds</font>, Button calls, SB completes, <font color="#CC3333">Hero raises</font>, UTG calls, Button calls, SB calls.

Flop: (8.00 SB) 3[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, UTG calls, <font color="#CC3333">Button raises</font>, SB folds, <font color="#CC3333">Hero 3-bets</font>, UTG calls, <font color="#CC3333">Button caps</font>, Hero calls, UTG calls.

Turn: (10.00 BB) Q[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, UTG checks, <font color="#CC3333">Button bets</font>, Hero calls, UTG folds.

River: (12.00 BB) 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">Button raises</font>, <font color="#CC3333">Hero 3-bets</font>, <font color="#CC3333">Button raises</font>, Hero.....