Re-solidify disturbed agar plates
Yes. It is quite simple actually. Do this inside a clean laminar hood:


Take a clean sterile scalpel blade or any other sterile long object. 1ml pipette tip would also do.
Cut the agar on your plate. Scrape off cleanly.
Put it in a sterile glass bottle.
Heat in microwave
Add kanamycin
Pour back


Another solution is to coat the agar surface with kanamycin just like spread plating. Check the appropriate concentrations.