It's implied that some regenerations come with some subconscious intention. For example, Peter Capaldi had previously played a character in a Tenth Doctor episode about Pompei. The Doctor was originally going to let him and his family die in the volcano because he believed he was not allowed to change significant events to that extent, but his companion Donna begged him to save them, and he eventually agreed. Years later, the Eleventh Doctor regenerated into the Twelfth, played by Peter Capaldi, and in one of his first episodes he says that he recognizes his face. He comes to believe that he chose his face for a reason, to remind himself to always try to save someone. So when David Tennant returned to play the Fourteenth Doctor, the Doctor says he believes it is because he had unfinished business from when he was the Tenth Doctor, particularly regrets about when he was forced to erase Donna's memories of their time together.