I had moved my music library to an external drive in order to free up some space on a crowded boot drive. Now that I've upgraded that drive to one with plenty of room, I want to move it back, but everything I've tried still leaves iTunes 11 accessing it from the external drive. Should I simply re-import all of the music files back into iTunes?

Conceptually, the simplest way to do this is to go to iTunes --> Preferences --> Advanced and reset the Media Folder location to the default (which will be in your User folder on the boot drive). Then clear your library and reimport.

To be sure it's set, shut down, turn off the external drive and start up the machine again. Then check the Advanced tab in iTunes Prefs to make sure it's using the reset location (it will be -- an annoyance I have is it resetting to the default whenever I restart since my externals boot-up slower than the internals -- so you shouldn't have any issues there ;-)

Will that keep my existing playlists as well?

I don't *think* your playlists will be affected (unless you delete or edit them) -- I don't believe they care where your media is kept so long as they can see it.

Resetting the Media folder location should be a non-destructive process, meaning if it doesn't behave, you can always point back to the files on your external drive and it should work as before =)

You could also hold down the Option key when launching iTunes to choose your Library.

More than one way to skin a big cat.

It won't affect playlists, those are kept track of in the iTunes Library folder.

Just be sure you have a recent TM back up in case it does get fouled.

Got hourly TM backups and duplicated files on two external drives. Not deleting those until I'm satisfied with the final results.