My son does great at math, but has problems with over-learning things. It could be that school gave her bad information at some point and 2+2 no longer quite equals 4 in her head. I'm not sure early math is all that relevant and perhaps worse than no math for a bright kid (when my son who was doing math by himself in his head, suddenly started counting on his fingers in first grade, I got worried.)
Maybe she needs a fresh perspective, search for Vi Hart videos. Or maybe try some higher level math concepts. However you approach it, I'd guess more of the same won't be the answer.
