I highly doubt that they'll retest her on the CogAT. It's poor testing practice to retest students (or adults) with the same instrument after such a short amount of time has passed. They may give her a different IQ test, but I can't see them agreeing to give her the CogAT again, so "prepping" her for that is a waste of time.
As others have said, prepping kids in any way for ANY type of standardized test isn't necessary. The test is normed against other kids who didn't receive any type of advance preparation or practice. An individual test may give you more info and a slightly more reliable score, but practice and prep isn't necessarily and can even be harmful because kids feel more "pressure" to perform when they take the actual test.
