The MAHARSH”O (Shabbos 152b) states that a NESHAMA “could” come back (reincarnated) up to three times. However, the NESHAMA of a perfect TZADIK – TZADIK GOMUR – does not get reincanted:
????”? ?????? ????? ???? ??? ?? ??? ???? ?
????? ??? ????? ????? ???’.
??? ??? ????? ??? ????? ????? ???? ??? ??? ??? ????? ???? ?? ?”? ???? ????? ???? ????? ????? ?? ??????? ???? ?? ?? ??? ???? ?? ????? ??? ?? ??? ???”? ??? ????? ???? ????? ???? ?? ??? ?? ???? ??? ??”? ?????? ?? ?????? ?????? ??? ??? ???? ????? ??? ????? ????? ????? ????? ???? ?? ????? ????? ???”? ??? ???? ?????? ??? ???? ???? ???? ?????? ???? ?????? ?????? ???? ????? ?????? ???? ??? ????? ??? ??”?:
However the BAAL HATANYA (Reb Shneuer Zalman of Liadi ZT”L)
(My explanation:)
For example, there are MITZVOS that only a KOHEN could fulfill them. So, even a TZADIK who was not a KOHEN, comes back in the next GIGUL as a KOHEN in order to fulfill the mitzvos of a KOHEN:
See the orignal at:
http://hebrewbooks.org/pdfpager.aspx?sits=1&req=49432&st=%u05d1%u05d2%u05dc%u05d2%u05d5%u05dc