Windows 8.1 Update 1 came out last week. There is a way as a user you can fetch this, but if you are an admin you can push this out. Let me walk you through this. If you are running Windows 8.1 you will need to upgrade if you plan to continue receive security fixes.
If you are running Windows 8.1, you can use Windows update to install the upgrade from 8.1 to 8.1 U1.
If you are an admin, be aware of an issue with using SSL for WSUS and this new patch. http://blogs.technet.com/b/wsus/archive/2014/04/08/windows-8-1-update-prevents-interaction-with-wsus-3-2-over-ssl.aspx
As an admin, you simply approve the upgrade (and a patch required for the update to happen) and then your machines should start getting updates.
System Center Configuration Manager
If you are an administrator for your corporate network, you can use Software Update Services to deploy the upgrade (once its added back in to WSUS again for synching) or you add the whole Windows CD as an application to SCCM 2012 R2 or any version that support Windows 8.1 as a client. You will want to invoke setup with the setup with /auto:upgrade and make it available to users via the software center.