Spoilers, Remember to use Spoilers [spoiler ] [ /spoiler]
Yah it was an excellent episode.
The rest of this post is a spoiler and conjecture.
So I had to think about it, and I think I figured out how. As she was dieing she changes the memory snow and the snow remembers her, her DNA, her Soul. At some point she will exists as a Doctors companion and as the Dalek Girl. Also remember the crash site is in the snow.