Persistent Attacker

 
Prerequisite(s): Sneak Attack +5d6
 
Benefit: If your sneak attack hits, your first attack against that creature on the next round is also qualified as a sneak attack even if it wouldn't normally qualify. Using this feat reduces your first sneak attack's damage by 4d6. The resulting second attack deals it's full extra damage.
 
Source: Complete Scoundrel