The documentation does mention a preview button which seems to have disappear.
Can I preview a receiver app on the Google Cast SDK Developer Console?
How can I force the refresh of an app(programmatically) on the chrome cast ?
You cannot preview your receiver on the developer's console. As for refresh, if you mean reloading the receiver app, use window.location.reload(true); you can even call that from the chrome debug console when attached to your receiver.