They're going to see what you've been doing the last year or else you are omitting very important information. That should tell them how you have improved your application. So if they don't explicitly ask, as long as the information about how you've improved your application is there (and it should be), you don't have to devote an essay to it. On the other hand, if that's how you want to use this essay and you've covered other topics (please see next paragraph), I see no harm in doing so.
In terms of "anything more," is there anything that you would like them to know about you that isn't covered in the primary or secondary? Anything that will give them more insight into why you want to be a doctor, the character traits and experience that you will bring to the practice of medicine, challenges overcome, some exceptional hobby or commitment that you have made, or perhaps a personal growth experience that you didn't' write about elsewhere.
Please understand that it is extremely difficult to advise someone on "anything more" without knowing "everything else" included in your app already.