This is a flying trapeze pun. a 'return' is when you swing out and back, remounting the platform at the end of your go, instead of dropping into the net - as beginners do. Saying 'many happy returns' to a flying trapeze artist on his birthday has a special meaning,
Here, I am referring to those beginners who come back for a second or third go. Maybe you didn't get the trick you tried on your first go and want to try it again, or maybe flying trapeze has that something special that calls to you.
So long as it hasn't been too long since your first class, you shouldn't have to repeat too much of the groundwork, we will talk you through a new move or decide what you are going to work on from your previous go, and then you can climb the ladder.
If you are thinking of joining the club, you might like to work on the prerequisite skills.