Updates matter, but mainly because they demonstrate interest. It is all about whether or not you will come if admitted at this stage. Have you written a letter of intent to the school? Also, if you remember one of your interviewers that you got along well with, email them and explain the situation. They may very well advocate for you to get in (even though I was just a student interviewer, I pushed for a kid to get in once and now he's a 3rd year). It was all about stats to the interview stage, and then somewhat about that when you were waitlisted. After that, it is all about passion. Good luck!