On the phone this is expected, but it should be there on the iPad:
It only shows IF there is actually something to improve. However, there may well be cases where it doesn’t find an existing improvement although it should.
So the question is whether your playlists contain such tracks, e.g., if there is a a higher-res version if you look manually, or the playlist has a non-library version that it should suggest to replace if you have an in-library version.
Examples would help.