See this post: ART new releases - #255 by lphilpot
Basically, you can run the installer pointed at C:\Program Files\ART every time and it’ll upgrade the current installation to the new version. It just doesn’t delete the previous uninstall key from the registry (which is pointed at the same directory), so you have to do that manually. See the next to last paragraph in the linked post above. It takes longer to open regedit and go to the key than it does to delete it. 
For convenience I have several “key keys” bookmarked as favorites in regedit: Local machine software, local machine run, local machine uninstall, current user software and current user run.