If you're using Chrome for Mac, ctrl+F5 nor ⌘+F5 will perform a hard refresh. Unfortunately, unless you're fairly knowledgeable when it comes to dealing with chrome browser files directly, the only way a regular user will be able to reset the cache for MArcomage is to reset the cache for all websites.
To do this, go to:
-wrench icon
--preferences
---under the hood
----clear browsing data
-----Then check "empty the cache" (nothing else need be checked), and clear the cache there.
While there are easier methods, using them will also clear your saved passwords and all other personal data. Clearing the cache for all websites is not a bad thing to do from time to time, so it doesn't bother me too much that I have to use this method to clear the cache for MArcomage when it's updated.