I would like to replace a songs that I have in my iTunes library with a higher quality version (and different filename).
These songs are listed in various playlists in my iTunes library, what would be the best way to update them on the playlists as well without manually going through each playlist to find find and replace?
Okay so I have found that if I delete the track via Finder (and empty trash), then finding the track in my Library in iTunes as expected it will say the file is not found. This will then give you prompt to locate the file, after selecting the new file all instances of the track will be replaced with the new location automatically by iTunes
That's a good solution for what you are trying to do. To answer you actual question, you can ctrl-click (or right-click) on the song and select "Show Playlists" and it should show you the playlists the song is on.
There's a nice tool from Doug Scripts which shows a floating window with all lists assigned to the selected song.
http://dougscripts.com/itunes/scripts/ss.php?sp=showinplaylists
