Question: If a person has not developed his point in the heart and therefore has no soul, then what is reborn in the next life?
Answer: Every person has a desire. Desire is a spiritual structure. But it could be ready for correction, change, and connection with others now, or it could not be ready yet.
However, in principle, every person is in their desire as an eternal particle of a single soul.
From the Daily Kabbalah lesson in Russian 11/25/18