[mylife]

has a dr ever regenerated in his former body?

[Ciaphas Cain]

has a dr ever regenerated in his former body?

Maybe. In the fiftieth anniversary special Tom Baker (Fourth Doctor) appeared as the museum's curator, telling Matt Smith's Doctor that in years to come he might revisit past appearances "but only the favorites".

[pepsi_junkie]

They had a special with a couple of the doctors when Matt Smith had the role and at the end Smith is sitting in a cosmic art galley and the curator stops in to say hello. it was Tom Baker and its hinted at that a time lord can revisit an "old favorite" face and your left to wonder 'was that....?'

https://www.youtube.com/watch?v=1cbQVfVfSrI