another note on identity

I was thinking yesterday, and I realized I don't really know what non-dualists think about conservation of identity. If everything is material, then doesn't the fact that all of your cells die and regenerate several times over the course of your life indicate that there is no conservation of identity overall? How could there be, unless there is some cell in the body designated as the identity holder and they keep trading off? You could argue that the identity comes from the patterns the cells interact in, and that new cells fill the same roll in old patterns, but then it seems identity wouldn't be purely physical then either.