D20r:Science

If you are affected by an ongoing mind-affecting, compulsion, or charm spell or effect and fail your saving throw, you can attempt the save again 1 round later at the same DC. You gets only this one extra chance to succeed on your saving throw.  

''Investiture:'' A rogue can choose this ability more than once: each time beyond the first grants her an additional saving throw one round later, so that a rogue who had chosen this ability twice would have a saving throw upon being targeted by the spell, a second saving throw one round later, and a third saving throw one round after that.