How to get refresh token with client_credentials?

Hello,
When using /oauth/token with “client_credentials” there’s no refresh token. How do I get it?
https://auth0.com/docs/api/authentication#client-credentials
Thanks

The specification states that Client Credentials Grant SHOULD NOT return a refresh token:
https://tools.ietf.org/html/rfc6749#section-4.4.3

To get a new token simply initiate another Client Credentials Grant flow to the /oauth/token endpoint. There is no user interaction involved, so your application can do this at any time.