No, just no. The only game that has ever come close to allowing this is Rift with you being able to change souls. That game was designed around being able to do so.
This game is not designed around being able to change your AC.
How about make some different choices while levelling to shake things up a bit? Get high level friends to run you through flashpoints? There are other options, you just have your blinkers on.
It's not BioWare's fault that YOU made the WRONG choice.