Air conditioning slow leak suspected

Air conditioning worked poorly two years ago. Did a recharge with dye but didn't get to bring the car back to check for leak (moved hundreds of miles away). Sure enough this summer no cool air again. Repeated the same service, recharge/dye, but the honda service guy didn't want to run a check after a week.

i am worried that the same thing would happen the third time---every time I ended up paying $120+ to recharge only to buy a coule of months cool air. Should I have it checked now or should I wait, and how long can the dye run out if there is a slow leak?

appreciate your kind advice.