Custom data connector with expiring refresh_token

The situation is:

I have an initial refreshtoken that I give as input, this returns me a new refreshtoken and accesstoken. The lifetime of the initial refreshtoken is ended after the first request. The accesstoken will be used for the bearer token and this will be used to get data from the other endpoints.

In Power BI I connect to my custom data connector with my initial refreshtoken.

This gives me a preview of the data.

When I click load it executes the data connector again with the initial refreshtoken (that is expired), this results in an error.

Is there a way in to store the new refreshtoken / accesstoken I received in the initial execution, so I can use it afterwards ? Or maybe another solution?