If you have valid student license, then you can download 2016 version from your students account page or using Virtual Agent:

https://ava.autodesk.com

(you need to enter "downloads" in the request field on the Virtual Agent page at first, then you will see version selector on the right side)

After installation you can activate 2016 version with the same serial as you have for 2015 version. The only difference is in product key, which is 777H1 for 2016 version.

Maxim