1.Don’t make any empty threats.
If you tell a student that you’ll make them sit down if they talk again, then you have to follow through. Otherwise, they won’t take you seriously.
2. Try not to repeat the same lectures.
As a ballet teacher, you will have to repeat some corrections. But notice, are they absorbing any information?

Other tips:
If they see you as a peer, it mat be easier for you to talk with them. Express your frustration. Don’t admit weakness, but don’t be too condescending. Make sure they understand that you know they are capable, and that you’re frustrated for them.
I’m no expert, but I hope this helps. Good luck!
-a teen student

I found a great video about this by former NYCB dancer, Kathryn Morgan. She suggests that for each night/show you come up for a story or theme for your character. Not only will it give you something new, it will help your acting. For example if you’re a snowflake, you can gather the other snowflakes and you could each pick a princess or dessert. Or if you’re a soldier make up a story of how you came to fight for the Nutcracker. Just get creative. Maybe it’ll help for next year.