When publishing to google store, you have a code version for your release, if you change this code and re-upload the apk, all the user will get an update notification, most user are set to auto-update, so in a matters of a days all your clients should be uptodate.
I never published to ios, but i am guessing it works the same.
The update status through the browser object is available if your uploading a plain html export to a domain.
Then, if there are changes to the offline.appache file the app will automatically re-download, you can access the progress with the expression loadingprogress, it runs from zero to one, you can also use the browser object to detect downloading of update and show a message and update ready to send a browser refresh command.