Right now you can't move a Take or Scene from one Audition to another within Slatable.
What you can do is save a Take to the Photos app and then re-import it into the new Audition or the Scene from your old audition.
If this is because you want to re-use a Slate in another Audition, please consider upgrading to SlatablePro where you can store as many Slates as you like in Settings > My Profile >Manage Slates. You can import as many 15 second clips as you like, in landscape or portrait. You can then add them to your AuditionDrop or your title cards in New/Edit Audition.