Unfortunatley, apart from spending all night rolling her onto her back there isn't much you can do. My girl slept on her tummy from the minute she could roll over. She wouldn't sleep any other way. My boy is now also sleeping on his tummy. He seems to have the longest and most peaceful sleep when he sleeps on his tummy. Even SIDS say that once they start to roll over there isn't much you can do about it. When my boy first started sleeping on his tummy he used to sleep with his face straight down into the matress, which scared me a bit. But after I had checked on him a few times and saw that he was still breathing I relaxed.