Bhagavad Gita, Chapter 8, Verse 19

The very same multitude of beings that existed in the preceding day of Brahma, being born again and again, merge, in spite of themselves, O son of Prithâ, into the unmanifested, at the approach of night, and re-manifest at the approach of day.

This whole real cycle repeats on its own, again and again, without needing to be restarted each time.

The word 'automatically' matters here. This isn't described as something that has to be deliberately reinitiated, it's a genuine, self-sustaining rhythm that keeps recurring on its own.