How people are getting to your program. Are they coming via a website, or is it a direct link to the GT program?
If it's a direct link to the GT program, you should be able to simply erase the content of the program and replace it with
*goto: http://therunlinkforyournewprogram.html
Anyone who runs the program will be automatically redirected to the program reached by this link. This will, however, create a "Please wait while we redirect you" GT message and loading screen while the program redirects.
If people are going to a website, there are much better javascript solutions.