From the 3.15 patch notes:
"Anivia, Eggnivia, and her skins (aside from Blackfrost Anivia) have received a Texture Update!"
3150 IP or 790 RP
Team Spirit Anivia
Limited Edition Skin ( Returning for purchase Feb 2014 )
Bird of Prey Anivia
Noxus Hunter Anivia
As mentioned above, Black Frost Anivia did not receive any texture changes because she already has a unique new model.