Don't end it, do a restart and go in a new direction. Big finish shows the ideas still work, they are just handicapped by certain writers and the fact that it is now hard to connect with the character. They need to ground the characters again, where the Doctor isn't known by every alien and just wanders into trouble and they don't have stupid story ideas like making him the president of earth. The easiest way is to bring back the Time Lords and have them not like what is going on and reset historical events. Then have them limit the Doctor slightly again in a way. Stop relying on special effects and go back to having a good plot.