Does Reincarnation exist
To ascend from its original level, a soul needs to reincarnate to do its Tikun. This Tikun of the soul is realized by the Gilgul (reincarnation) and/or by the ‘Ibur (attachment). While Gilgul is the reincarnation of a soul into a body from the time of its birth until its death, the ‘Ibur is an attachment of another soul to his own soul, that could come and leave at anytime.
If man does not do the Tikun for the level of his soul for which he came, he comes back and reincarnates in a new body for a new life. As long as he undertakes the Tikun of his soul in three reincarnations, he will come back again and again as needed, to complete his Tikun. However, if he maintains his wrong behavior and neither performs nor advances in his Tikun, he will not return after the third reincarnation.
There are different reasons why a soul might have to come back and reincarnate. It could be to repair or rectify an act for some damage he caused by his wrongdoings, or by not accomplishing the Mitsvot – commandments. The secret and reasons behind the accomplishment of the Mitsvot is to help, or make the Tikun of the soul.
As there are 613 parts to the soul, and 613 veins and bones to man, similarly, there are 613 Mitsvot and 613 lights in each Sephira or configuration. Each Mitsva corresponds to one part of the soul and of the body; by performing a positive commandment or avoiding a negative one, the corresponding part of the soul is reinforced and repaired. Failing to perform the positive Mitsva or to avoid a negative commandment causes direct damage to one’s soul and requires repair in this life or in a future reincarnation.
It is only by getting another chance to do or undo what he should have done or not do, that man makes the necessary Tikun of his soul, which can now rise to the higher realms and rejoin its source.