There has been several discussions I have had the pleasure of being involved with, in regards to this topic, as a result the following was determined.
Should the body die, by means other then old age, but even then depending on the complication that has arisen, the focused recalling of all the disciplines of VTM should in theory recall the body from the shock, because in that moment the brain cells become realigned, by stagnating, or by rewiring themselves.
Should the soul inhabiting a vessel desire it the means for incarnating by the three versions of forced incarnation as best described by Carroll as the White Rite, Red Rite, and Black Rite, are all viable means of incarnation.
There is also some interesting concepts about taking into the flesh the infernal energies of Ahriaman, and becomeing a spiritual demon, that goes and incarnates at will on this plane in accordance with the needs in different regions.
As well as some less convential means such as photographic transferences much like stories such as The Picture of Dorian Grey, as well as severing off aspects of your soul, as found in the Harry Potter books, these do work as viable means for a form of survival.
There is also a theory I have developed on the matter, where one takes a book they have written of all the spells they would pass on, they then bless the book to be a vessel for the spiritual power, and then blesses a ritual tool that accompanies it, such as a simple ring, that containes the soul after the death of the mage, It then can be recalled when either some one of the same blood line, or someone who has come by both, read the inscriptions within the book, and the soul and power of the mage comes and possess the flesh of the one who wears the ring. This possession holds till the death of the mage where the soul goes back into the necklace, or into the book depending if the book is cast with stones into the binding and made of sacred metals. As for specifics, create your own. I will go no further.
