Clara turns to the crack in the universe. "Help him change the future," she says to the Time Lords. She kneels down by the crack so she can whisper an answer to their question. "His name is the Doctor. All the name he needs, all you need to know about him. And if you love him... help him." Do they love him? Apparently so, because the crack seals up, just like that. In all the many hundreds of years and the Doctor never thought to just talk to them? "Listen, I can't answer you, no matter how many times you repeat the name of the show, but you really need to back off because you're causing a lot of problems over here." Maybe pass a little note through to the other side?
After a long, long climb, the Doctor reaches the top of the tower, where he addresses the Daleks. "You still can't work up the courage to shoot me, can you?" he asks. "You're still worried I've got something up my sleeve!" Defeated, he says he's got nothing. But then the crack appears in the sky, and from it comes a golden vapor that finds its way into the Doctor's mouth. His face is all surprise and delight as he realizes what's happened. He begins to regenerate. "You will die, Doctor," drones a voice from the Dalek ship. "This is the end of you!" The crack seals up again, having delivered its precious parcel of extra life. The Daleks freak out. The Doctor prances about, swinging his cane. It's going to be a big one, he promises them, as bolts of energy shoot from his hands. Clara warns the townsfolk to get inside. The Doctor hoots and laughs, and blasts the Daleks out of the sky. "Love from Gallifrey, boys!" With one final, dramatic gesture, he explodes with light, taking out the Dalek ship and laying waste to half the town.
When the dust settles, Clara rushes into the TARDIS. She finds the Doctor's old clothes strewn about the platform around the console, next to a bowl of fish fingers and custard. The Doctor walks up to her, in fresh clothes, wearing his old/young face again. "You didn't even change your face," she says. "This is just the reset," he says. The process is underway and there's no stopping it. He's a bit wobbly on his feet as he starts up the TARDIS. With a regeneration underway, perhaps now is not the best time to embark. The Doctor waxes poetic about the transience of life. Everything changes. Everything ends. "Any moment now, he's coming," he says. "Who's coming?" Clara asks. "The Doctor," he says. "But you're the Doctor," she tells him. "Yep, and I always will be," he says, "but times change, and so must I." With tears in his eyes, and his hands beginning to glow again, he imagines that he sees young Amelia Pond running about the TARDIS. "I will always remember when the Doctor was me," he says. Grown-up Amy approaches him with a smile and touches his face. "Raggedy man, goodnight," she says.