Good that you found it early! Yes, you should reapply to catch newly hatching nymphs. I usually do a visual inspection every 3 days, and treat once a week for 3 weeks. On catts, I usually use rubbing alcohol and paint (with a brush or Qtip) the pbulbs, especially the papery stuff and around old flower spikes/sheaths. The adults move quite fast so yes, do isolate. And check the neighbors carefully.
Mealybugs are easy if you catch them early.