I HATE mealybugs for just the reasons you have listed. Using alcohol or Insecticidal Soap are your best options for ridding yourself of them, BUT they will never be completely gone. You are in for a lifetime of mealybug eradication diligence.
Most pesticides work only short term as the surviving mealys become resistant and the pesticide doesn't work anymore. Insecticidal Soap and rubbing alcohol are contact sprays that work by softening the shell of insects so they never build up resistance. The mealybugs are not in the soil so repotting is not helping rid your plants of them. But, they are so tiny that they can hide in the pores of clay pots, in the wood grain of your table top and any other surface with a texture. Don't reuse your pots without sterilizing them in a bleach bath or the dishwasher.
Put the alcohol in a spray bottle and drench the plant, every nook and cranny, then blast it with your sink sprayer. Wait for an hour and inspect the plant, spray and rinse again if you see more mealys (they seem come out to replace their dead buddies). Keep repeating until you don't have them crawling out of hidden spots. Inspect your plants daily and then, eventually, every time you water and use a Q-tip soaked in alcohol to get rid of any you see.
Good luck!
