No chance this year of face lift considering the below:-
A6 - First deliveries spring 2011, facelift announced autumn 2014 and deliveries first weeks of 2015.
A1 - First deliveries autumn 2010, facelift announced winter 2014 and deliveries start spring 2015.
Q3 - First deliveries summer 2011, facelift announced winter 2014 and deliveries start spring 2015.
A3 - First deliveries autumn 2012.
As a high volume model in the range I suspect it will follow a timeline similar to the A1. A good guess would be facelift announced late 2016 and deliveries early 2017. Demand is still very high. The engines might get some slight tweaks but it would be at the model year change time.