Okay I have found a way to get beats that you have changed by using replace in AD2
1st Amend the beat then drag into your shorlist area.
2nd Drag that file from shortlist into explorer (e.g. "E:\Users\Nick\Documents\Addictive Drums 2\External MIDI Files\Eclipse\" The folder must reside under "\Documents\Addictive Drums 2\External MIDI Files\"
3rd In AD2 remove original beat from Shortlist
4th Rename the file that will be called AD2Beat.mid to whatever you require (note that _V_ will give you a variation (e.g Communion_V_Intro.mid , Communion_V_Verse.mid etc.)
5th Delete original file AD2Beat.mid
6th Refresh Midi Library back in AD2
7th Hey presto the beat is back in AD2 under the folder you copied it too.
Hope that helps