Remember me with OAuth2 in SPA

I know the concept of OAuth2 and OpenID. in our application authentication is happening through OKTA and we receive access-token in a response. Our architecture is a microservice-architecture and we are using EmberJS at frontend.
we have to implement remember-me functionality it will keep the user logged in for the next 30 days. I did some study on it and came to points that will satisfy my requirements.

1. keep user session active for 30 days in OKTA.
2. refresh access token periodically based on its expiry time.

How this refreshing will work if browser is closed? Let's say a user is logged in and closed the browser then reopened it after 3 days.