Change the target of target spell that targets only a player. The new target must be a player.
Insult, like an arrow, is beyond control once loosed.
Official Rulings for Rebound
4/1/2008 : You can't use this on a spell unless the target spell is an Aura or uses the word "target" in its text. If it isn't an Aura and the word "target" is not there, then the spell does not target a player at all—it just affects a player without targeting them.