It is possible to programatically check from you app, if there is an update. See https://social.technet.microsoft.com/wiki/contents/articles/21672.now-check-for-updates-of-your-app-inside-your-windows-phone-application.aspx.
If there is an update, just show the user sa message about the need for an update and redirect them to the store, disallowing im the usage of the outdated app.