From what I've been told, it's important to have kids fit properly.  Now that doesn't mean you have to go get a full professional fitting and buy brand new clubs.  But make sure she is using the appropriately length club (maybe an extra inch or so for growth) and most importantly, the correct flex.  If you can find clubs with the correct length and flex, you should be good.  Otherwise, I'd look into getting whatever clubs you want and having custom shafts put in them.  Then you can upgrade just the shafts as she gets older.