How to Update Aptana Studio to the latest?

I have Aptana 3.1.1 installed and want to update it to 3.1.3, the latest version. How could i do that?

I have tried the "Check for Updates" under "Help" menu, and it said "No updates were found". I guess that a update site needs to be added, is it?

Hope I don't have to download the latest version to update Aptana...

Thanks for any help.

Solution

The problem is that the update sites list is empty. To add a list, just import the list in the .xml file provided by Aaron K here.