There is no one size fits all answer to this. It depends on your application and it's deficiencies. This isn't about something that is "supposed" to be done. This about addressing the aspects of your application that did not make you attractive to medical school. Your personal statement is a small part of your application. It is unlikely that it was the primary reason for you not getting into medical school. However, it can easily be a contributing factor and so it should be reviewed and improved upon, just like the rest of your application.