Question:

General Release refers to a set of Vault production servers that receive software updates approximately every 4 months. 

Limited Release refers to a set of Vault production servers that receive software updates approximately every 3 to 5 weeks.

Is there a way to change a General Release Vault to a Pre-Release Vault?

Answer:

It is not possible to change a General Release Vault to a Pre-Release or a Limited Release Vault.

Related Documentation:

Vault Help Documentation: About Vault Releases