[theory]cbet AK after reraising

[BetweenTheLines]

Ok this a general problem I had in the last days,I think
reraising AK preflop is standard but at the moment it's like
burning money for me,think I have leaks in playing reraised pots.
for example:
Full Tilt Poker - No Limit Hold'em Cash Game - $0.10/$0.25 Blinds - 5 Players - (LegoPoker Hand History Converter)

SB: $18.10
BB: $30.70
UTG: $25.15
CO: $21.30
Hero (BTN): $23.15

Preflop: Hero is dealt K[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/heart.gif[/img] (5 Players)
UTG calls $0.25, <font color="red">CO raises to $1.10</font>, <font color="red">Hero raises to $3.90</font>, 3 folds, CO calls $2.80

Flop: ($8.40) 9[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/club.gif[/img] 6[img]/images/graemlins/diamond.gif[/img] (2 Players)
CO checks, <font color="red">Hero bets $5.50</font>, CO calls $5.50

Turn: ($19.40) 2[img]/images/graemlins/heart.gif[/img] (2 Players)
CO checks, Hero checks

River: ($19.40) Q[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">CO bets all-in for $11.90</font>, Hero folds
Uncalled bet of $11.90 returned to CO

Pot Size: $19.40 ($0.95 Rake)

I mean there is often a board like this if you miss,undercards sure (ok the example is bad because its very connected). But is there value in cbetting? I mean he will not fold a lot of pp here?Another question how big to make the cbet,people say in rr pots you can make your cbets smaller like half the pot,but seems that people see that as weakness if you only bet half pot?And what about the normal donk-callingstation if he calls the rr will he often enough fold to make it profitable,?

Another sidequestion in which scenario do you like coldcalling preflop with AK?

So maybe I have just shortterm problems but I hope that some
experienced players can help me to improve my game in these
spots.