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

{ "error": { "message": "Missing redirect_uri parameter.", "type": "OAuthException", "code": 191, "fbtrace_id": "BHvng7s53ra" }}