How do I get in or out of Practice That mode?
Just say "Hey DJ, Practice That" or hit the "Y" button on the controller ANY time you are dancing to enter Practice mode. You'll be able to immediately practice the moves that you were just dancing as many times as you want.
When you are ready to return, say "Hey DJ, got it" or hit the "Y" button. You'll get dropped back in the song right where you left off!