Howdy Mark,
The Recently Added playlist is a Smart Album that has specific settings to automatically add new content to that playlist. It can be recreated manually if accidentally deleted, you can use this article named Archived - iTunes: How to create a Smart Playlist found here http://support.apple.com/kb/HT1801.
- Choose File > New Smart Playlist.
- To have iTunes add songs that match specific criteria, make sure to select "Match the following rule," then make your selections from the pop-up menus.
- For example, you might want iTunes to only add songs that are by a particular artist, or songs with at least a four-star rating.
- To add additional matching criteria, click the Add + button.
Here are the parameters to use when you create the new Smart Album:
1. Check the box that says Match the Following rule:
2. Change the first set of criteria to Date Added, In the Last, 2, weeks.
3. Add another line for criteria by clicking the + button
4. The second set of criteria should be as follows. Media Kind, is not, podcast.
5. Uncheck Limit To, and Match only checked items, and check Live Updating.
That when that is done you will have a new smart playlist that you can rename to Recently Added by double clicking the smart album name.
All the very best,
Sterling