Have a google or search on here for Automatic Front end Updater.
Essentially you have a storage location that holds a master copy of your front end.
You have a version number embedded in or associated with the local copy of the front end.
You have something that compares that version to a master version, and if required copies it to the local location.
The master file location should be read only so that no-one (except you) can open it or overwrite it.