In most cases a student visa can be extended for the entire study period.
Student visas can be renewed in Kazan provided that:
Kazan Federal University cannot be held responsible for the problems you might face after your arrival in Russia, if you have neglected the instructions given above.
As the process to get the new multi-entry visa takes at least two weeks, we strongly recommend to you to arrive to Russia no less than 20 days prior to the expiry of your one-entry student visa