Firstly, I should say that I don't know for sure...

My assumption would be, if you have 'use' or 'require' at the start of your script, then you've already got that module loaded and it won't be loading again until the program is re-started. Certainly this has been my observation with modules of my own that I've modified during developing various tools...

Safest bet - stop the application, make your changes, restart application.

If you want to know for sure, set up a similar scenario, have the module print 'foo' every second. Start the app, modify the module to print 'bar' and see if it effects it