A new face, body, and mind always mean a change of wardrobe. Often when he regenerates, he finds his old clothes no longer fit, and that’s even if they survive whatever caused his regeneration.
One of his first tasks, once everything has settled and his new brain can think coherently, is to find something to wear that suits not just his physical appearance but also his new personality. It can take a while, trying on countless outfits, but he knows the right look when he finds it.
Not until he’s fully dressed does he finally understand the person he’s become.