Party Poker No-Limit Hold'em, $ BB (8 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG ($124.50)
Hero ($113.55)
MP1 ($272.55)
MP2 ($101.60)
CO ($86.50)
Button ($133.88)
SB ($24)
BB ($101.65)

Preflop: Hero is UTG+1 with K, A. SB posts a blind of $0.50.
1 fold, Hero raises to $3.5, MP1 calls $3.50, 5 folds.

Flop: ($8.50) A, 8, 6 (2 players)
Hero bets $7, MP1 raises to $14, Hero calls $7.

Turn: ($36.50) 2 (2 players)
Hero ???

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Opponent is a 15/6/3 over 100 hands.

What's your play here, and your river plan if called?