I just recently did the boiling water. Not only did I use a seringe and stabbed it, but I also kept on squirting it and it looked like it just melted and turned black. I thought I got rid of it for good.
Sure enough......a week or so later there are two growing from the same place!!
So I got a peppermint shrimp. After a couple of weeks he found them and I haven't seen them back yet!
If you decide to get a Peppermitn Shrimp just remember that if he's getting food from another source he won't touch the aiptasia. Oh, and make sure it's a "real" peppermint shrimp, some look similar (don't remember the type). They don't work for everyone but I've had good luck with it.