This must be possible, but I'm not finding how to do it via any search string I can make up.
I have a sequence in which a cardboard carton pops out of a machine, drops onto a conveyor (where a text talk balloon appears), then box and balloon slide along the conveyor, and move out of the frame. 
I need to have several boxes pop out and move off stage over a minute or so -- how can I simply re-use all the stuff in the original box + balloon -- that is, just loop the activity several times?