there is no place to update to Lightroom cc 2015..
Lightroom 5 tells me there is an update but sends me to the web and it tells me to update via the creative cloud but there is no update on the Creative cloud..
it said to sign out and sign back in but to no avail it doesn't work,,,
Then you'll probably have to do what a lot of others have had to do, including myself. Open the preferences in the creative cloud application manager and sign out. Then sign back in again and LR CC should be available for installation.