It took me awhile to find this, so I figured I’d share (these instructions are for Mac – I’m assuming Windows is similar).
Preferences → Under the Hood → Content Settings → All Cookies and Site Data… → Search for the site → Expand the site → Click Session Storage → Remove
Additionally, you might have to clear the regular browser cache as well. I just had a stubborn file that wouldn’t grab the new version until I did this.
Preferences → Under the Hood → Clear Browsing Data… → Select Obliterate the following items from: the beginning of time and check Empty the cache → Clear Browsing Data