The standard 'Program Files' exclusion is specific to your local Program Files folder. You can add a generic Program Files filter, ie exclude ALL file paths with Program Files in the name, by adding:
-Program Files
For example this would exclude paths with the term Program Files at any folder depth
\\computer1\C$;\\computer2\C$;-Program Files
That would probably be sufficient for your situation but depending on your needs you can get more specific, e.g.
-c$\Program Files