Found this note on the "About the XFINITY TV Sports Remote app
" page (»customer.comcast.com/help-and-su ··· ote-app/
) on the Comcast Support site (which was updated on August 6th):
Please note that the XFINITY TV Sports Remote app is no longer available for download from the App Store. If you currently have the Sports Remote app installed, you will continue to have full functionality when using it, but will not be able to download and install the app again should you uninstall it.
Don't know why it should have disappeared from your iPad though.