It's not really an after-"life". It's more of a transitory period. When we die, our souls leave our bodies, and if we are Satanists, we go to "Hell" (Not the xtian version, mind you), where we wait for reincarnation.
P.S., when I say "Satanist" I mean someone who is loyal, and works for Father Satan. Not someone who does the dedication ritual and then doesn't do anything else, and expects to be "saved".
According to old lore no im not a high priest i do not know exactly but i am personally one whom has experience with reincarnation therefore i believe that most of us who give our selves to satan reincarnate afew can choose to stay behind to help others etc. and i do not know as to a true afterlife but im certain a high priest or priestess can help you.