Well you can set the expiration span as it's described here: https://azure.microsoft.com/en-us/documentation/articles/power-bi-embedded-app-token-flow/ (search for exp). But my question is more about best practices around how the embedding application can catch a situation where the report embed token has already expired and must be refreshed. Currently when you hit a dashboard where the token has already expired it just shows ugly errors.
Thanks
Daniel