Deleting Songs from iPod Nano Not in the Playlist

I have a playlist that I use to synchronize iTunes with my iPod Nano. The synchronization process adds new songs to the iPod Nano very well. However, it never deletes them. I have way more songs in iTunes than my iPod Nano can hold. So, I need to reshuffle the list once in a while.

How can I get iTunes to delete songs off the iPod that are not in the Playlist?