Thanks Vinoth for your reply! I tried opening Copilot Studio in an incognito session as you suggested, but that didn't generate a new token. Maybe the token information is stored on the server side and a new one won't be issued until it is expired.
That's a good suggestion on creating a middleware function; I was thinking something similarly. We are in the process of setting up a call with Microsoft on Copilot Studio, so I'll post more here once we've discussed the matter with them.