Keeping your Genius information up-to-date
Genius is a free service from the iTunes Store that creates playlists and mixes of songs that go great together, and makes recommendations based on the songs in your iTunes library.
When you turn on Genius, iTunes collects information about the songs in your library and sends that information anonymously to the iTunes Store, where it’s compared with all songs available at the iTunes Store and with the libraries of other customers. Your iTunes library is then updated with the newest Genius information. The amount of time this process takes can vary according to the size of your library, connection speed, and other factors.
The iTunes Store updates its Genius data constantly. Your own Genius information is automatically updated once a week when iTunes is turned on. Sometimes you might want to initiate an update manually; for example, when you import music to your iTunes library from a CD or a website.
To update your Genius information manually:
Choose Store > Update Genius from the iTunes menu bar.