What is the correct way to refresh Facebook OAuth2 access token after it expires?

Question

As I understand it, this is the basic process for new Facebook iframe canvas apps using the OAuth2 API in a nutshell:

1. Redirect to (or have user click link to)

Answer 1

if user has already authorized your application and access token expired. you can redirect user to authentication page again. but oauth dialog doestn't show because user already authorized your application. he will redirect to redirect_url parameter you used.