I just did this.
What I had to do was chat with a rep for a while.
Basically, you have to cancel your membership, then re-purchase. It's a pain. But, as long as you do it with a rep on chat, you should be able to avoid any cancellation fees or anything.
Just make sure your fee is waived and your next payment s your new price (student price).
I wish there was a button in the account that can just allow you to apply for a "upgrade".