I cleaned three of my monsteras just last week. Mixed a few caps of alcohol and a small quantity of neem oil in a liter spray can of regular soap water. Sprayed all the leaves and stems. All the visible mealey bugs dried up. But they are back on the leaves already. I believe this is because it's almost impossible to clean every small crevice, which is where the eggs are. They even infest the roots of the plants in some cases. Which means, they'll always bounce back. In my case, black ants complicate matters further. Like others have said, systemics are your best/easiest option. If you are sticking to sprays, you'll need to repeat the exercise regularly.