"not transferred in the last xx days" setting?

[grenert]

I am trying to find a way to continually put new music on my portable device. I use smart playlists and auto-sync to send music to the player. There is a "last played" option in smart playlists, but I don't play music on my computer, and the computer doesn't know that I played a transferred song on my portable device. Is there a way to replace songs on a smart playlist with new ones after they are played on a portable device? I was thinking that if there were an option in the smart playlist to only select songs that were not transferred to the player in the last xx days, that could come close to what I want.

Thanks for your help.