50NL bet sizing

[pokahpaul]

PokerStars No-Limit Hold'em, $0.50 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB ($66.95)
UTG ($28.80)
Hero ($52.55)
Button ($59.20)
SB ($67.25)

Preflop: Hero is MP with A[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/club.gif[/img].
UTG calls $0.50, <font color="#CC3333">Hero raises to $2.5</font>, Button calls $2.50, <font color="#666666">1 fold</font>, BB calls $2, UTG calls $2.

Flop: ($10.25) 9[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets $8</font>, Button folds, BB calls $8, UTG folds.

Turn: ($26.25) 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero bets $15</font>, <font color="#CC3333">BB raises to $56.45</font>, Hero calls $27.05 (All-In).

River: ($124.75) K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players, 1 all-in)</font>

Final Pot: $124.75

villain was a bit crazy, loose, way aggro

i thought a second barrel was appropriate as i picked up the flush draw and thought that i might be able to extract a little more value from an underpair or weak 9.

my question is, when firing a second barrel against a tougher opponent, should i bet an amount that'll price me in for the draw should villain move in over me?

as played, i think for this hand i should have checked the turn and called a reasonable river bet