I need to add new year to my inventory value cube date dimensions

My inventory value cube has date dimensions which had end date until last as the new fiscal year started I need to add new year to the date dimensions. I am looking for some experts opinions hownincann add new year to date dimensions and what are the pre and post steps that are needed to follow. 

My current version of dynamics is. Ms Dynamics 2012R3

Any advice is greatly appreciated. 

Thanks Momen