Romana was able to choose what she looked like.
As did the 2nd Doctor before becoming the 3rd one.
Matt Smith was the reboot when he got 12 new regenerations.Literally every regeneration is a soft reboot.
A hard reboot is going to do WHAT? NOTHING.
Just have her regenerate into Ian Chesterton's son-Alfred Enoch. Yes that is Alfred's real life Dad (the actor who played him is).