You can install the update through the Creative Cloud desktop application, or you can check for new updates by choosing Help > Updates. More info on the update here: https://blogs.adobe.com/creativecloud/premiere-pro-11-1-1-update/

If the update isn’t available for you, you can sign out of the Creative Cloud application and then sign back in. Some customers reportedly had to perform those steps to be notified of the update. Link: https://helpx.adobe.com/creative-cloud/help/sign-in-out-activate-apps.html