Re-doing a round strikes me as more like 6-8th level, but certainly fits the profile for foresight. There was a psionic class that had that as a shtick that might be worth reveiwing. This is potentially even more potent. Look at the possible options for a wish spell - I think this is one of them already and the additional casting cost there is MASSIVE above and beyond the spell level.
I'd also use a standard rule for the whole foresight discipline that a character can only ever have a single foresight effect pending. My feeling being that you can gain one "foresight charge" that is a predictions or prophecy and can be cashed in for whatever depending on the spell that gave it to you, but you can't have more than one (competeing timelines, or just plain naked mechanics to restric abuse and confusion). That way you can't stack a bunch of trigger on demand bonuses and then use them all at the same time...
Good ideas there
