How to move entries from one channel to another
Currently there isn't any core functionality in Craft for duplicating/moving entries between sections. I think this has been brought up a few times before, but I'd recommend heading over to Craft Feedback and posting up about it there!

Anyways, back to your question. I did post something similar to this at the end of last year. I haven't used this particular code in a long time, and I'm afraid I can't currently test it for you right now, but it might be worth giving a try.

It's also worth noting to take database backups before trying this in-case things start getting scary!