That's what I'm wondering too. Obviously they are not just going to make a decision based solely on if you are there or not, but I thought that maybe it's a good way to let them know that you are still interested? On the other hand, the day seems like its more focused on those who haven't already applied, so that's just why I was wondering if other current applicants will be attending
You can also send a letter of intent if you're still interested in the school.