Hi Deziner. Welcome. As long as you've got it on the bench there's a number of things you can check. The obvious being change all the fluids including front and rear brake fluid, clutch fluid, engine oil and final drive, and engine coolant. New air filter and check to see if the secondary throttle plates are still installed. Fork suspension fluid could be changed and the steering neck bearings checked. You could check to make sure the factory recalls have been done.
http://www.kawasaki.com/ownercenter Drive splines could be inspected and a bit of moly paste applied. Might be a good time to replace the TPMS batteries. All depends how deep you want to go.