Refresh access token to be used for Power BI Rest API

Hello

I am embedding report into custom application using Power BI Rest API

Ref : Embedd using Azure active directory , power bi account and Power BI API

In this flow user is authenticated by auth2 authentication. first i get autorisation code and based on autorisation code i get access token. lifespan of access token is 1hr.(3600 sec)

Is there any way to refresh this acess token. I tried with  refreshToken method of AD APIS , but it returned me unauthorised error.

Please let me know if anything is available to refresh the token.

Thanks In advance.