The reason you can't go to a new server is because you are seeded with a server so everyone starts about the same time. (I would love to move to a server that just started two weeks ago - DOMINATION!
As for the OP - yes, you must face the same people over and over until you can beat them.
Replies
Step 1: Delete current account
Step 2: Create new account
Step 3: Begin your farm anew
You can't delete accounts.
So -
Step 1 - create new Google play or Gamecenter account
Step 2 - Begin your new game
As for the OP - yes, you must face the same people over and over until you can beat them.
You forgot Step 3 - Use the Vader exploit to get him to 7* and they'll move you to the cheater server.