Arjun enquires if one has to start all over again (6.38) while practising (vairaagya) with shraddha (trust), but dies on the path before he attains this (6.37).
Krishna assures that such a person who has fallen from yoga will never get destroyed (6.40); is born in the home of the pure or wealthy (6.41) or yogis, otherwise, such births are harder (6.42). United with the knowledge acquired in his former body, he strives for perfection (6.43) and transcends with practice (abhayas) (6.44) to attain the supreme goal after many births (6.45)
The earthen pot is the best example to understand the intricacies involved. When a pot is made it engulfs some space and when it is moved from one point to another, the space inside it doesn't move along with it. But the pot does whilst always containing some space. Secondly, depending on the contents stored in it, the pot acquires certain characteristics like scent etc. Even after the pot is broken, the smell is likely to continue for some time. If that space with the scent is engulfed by another pot, it will carry the previous characteristics of that space.
The same analogy can be applied to the human body, it being the pot, space inside being atma (soul) and the entire external space as paramatma (supersoul). When the body is unable to discharge its duties, atma changes the body like old clothes. (2.23)
In contemporary science, the mathematical model of reality suggests that there are about 10 dimensions. While the example of the pot is easy to grasp in our three dimensional existence, Krishna's assurance as paramatma is at the level of multidimensional existence where many attributes are carried forward from one life to another. This assurance can help us to start a journey at any point of time in life.