Just got all these replies so I will do my best to answer all of them:
First of all, Nietzshe believed that our world happens in a spiral, from birth to death to rebirth, though changing with every cycle (I don't have the exact resource, I heard this from a proffessor).. In his criticism on Plato, he criticized Plato's theory on separation of body and soul, not his theory on reincarnation. He does state, however, that Plato could have been holding back some of his beliefs because of the time in which he was publishing his philosophies. (this can be found in his work, The Problem with Socrates)
On the aspect of whether or not we have a soul, this is a question that no one can really answer for you. I believe that we are carnal beings, and our body is in connection with our soul during our lives. I do believe, however, that our bodies are mortal and our souls are immortal.. our bodies are simply the vessel that carries us through our lives, allowing us to experience pain and pleasure. If you believe that we are soulless, then my advice to you is to simply carry on your existance as a carnal being of the flesh.
In response to why I believe in reincarnation, there are several, several reasons, but I will mention the one that I think would best respond to your questions. So many people live their lives fearing death and the unknown. By believing in immortality through rebirth: the everlasting chance to learn, make mistakes, and try different things, has helped me transcend that. (some people simply believe in a nothingness that ensues death - while this serves their purpose, it makes life seem empty and pointless to me - what, if there is nothing, are we trying to achieve then? what is the point of our quest for knowledge?)
Mostly I was wondering, out of curiosity, what other spiritual views Satanist had of the afterlife (besides reincarnation). I've heard a lot of rejection of all beliefs, including an afterlife or a soul, but as far as spirituality in Satanism (some people may see this as an oxymoron), I have only heard of reincarnation.
"Today I love myself as I love my god: who could charge me with a sin today?
I know only sins against my god; but who knows my god?"