No need to use new keys, simply install update from kaspersky site listed above. Existing keys used for version 8 will work for version 9.

To change keys, close your internet connection, then click at "License" found at bottom of the window when you open Kaspersky. You see a red color "X" sign.
Click at that sign to delete the key, and then select activate new license. It will have an error message as it cannot connect, and then "activate using key file" option will appear, then activate using new keys as usual.