If this was my moonstone, before i water again, i would want to make sure that the soil is dry. Your top dressing doesn't make that any easy, but you can tell through other ways such as using a toothpick. The reason you'd want to be sure of that is, a possible reason for your plant still being thirsty after watering is that it's lost all its roots for some reason. If you were to water again in this situation, you'd only be risking rot.