Did you also have to tell your users to press Ctrl+F5 to get the updated assets?
Actually I did!
What I do now is this: there is a websocket connection always open with the connected browsers, and when there are some assets that reallyreallyreally should be refreshed, I send a command though the websocket and the browser (after a few client side checks, like making sure the user is not in the middle of filling out a form) executes ´window.location.reload(true);´