In Buddhism karma and rebirth are treated as sheer brute facts and nothing more. As such, the Buddhist conception of karma is not like that found in some theistic religious systems. Karma doesn’t serve any purpose within some supposed divine plan. It wasn’t ordained by any God to serve as a guarantor of cosmic justice or a means by which humans might evolve towards union with God or some such ultimate end.
Likewise, the Buddhist conception of rebirth is not the same as Nietzsche's "eternal recurrence" or analogous ideas among New Agers.
The idea that a suicide would have to come back as such and such, in order to experience such and such, in order that such and such lesson be learned.... etc. etc. — this presupposes a conception of karma and rebirth that is alien to the Buddhist world view. It assumes that rebirth has some sort of evolutionary teleology to it (as in Theosophy, for example), but in an atheistic system like Buddhism this is out of the question.