Soft Agar Substitute
The good news is: You don't need any agar in your plating media, since the bacteria grow on the surface anyway and the plate can take up some additional moisture from your plating media.

What I usually do is to dry the plates for a while (and also let them warm up, since they are stored in the fridge) with the plate upside down and opened a bit. Contamination is usually not a problem here.

Then I dilute the cells in an appropriate volume of media, then plate about 50 to 100µl on the agar and spread it with a Drygalski spatula. Put the plate in the incubator and everything is fine.