Complex sentence: Every spring he is reborn, with his DNA altered, but retained his memories, and then ages rapidly until winter when he dies, only to be reborn again the next spring by crawling from the husk of his own skin.
Split into simpler sentences: Every spring he is reborn with the same DNA and memories and then ages rapidly until winter when he dies. Only to be reborn again the next spring crawling from the husk of his own skin.