Microsoft has released an update for Microsoft Skype for Business 2015 (Lync 2013) on November 7, 2017. This update also includes the new Skype for Business client. The version number of this update is 15.0.4981.1000.
The updates above are for the MSI codebase. C2R updates for the O365 channels are documented on the Office 365 client update channel releases page. Visit the Overview of update channels for Office 365 ProPlus page for more information about the O365 channels.