I have lots of experience with lop ear infections with my Bindi Loo.
Is it an outer ear infection? What is the name of the drops and the cleaning solution?
How often you clean the ears will depend on two things: how much wax production there is and the type of solution you are using. Bindi gets so much gook in his ears that I have to clean them about every 2 weeks. If there isn’t much build-up, there is really no need to clean them often. Over-cleaning can lead to too much moisture as well as the ear going into over-drive and making more wax to protect itself. I have a small flashlight I use to check his ears at least once a week for build-up and redness. If your bunny gets one ear infection, it’s very possible he will get another down the road.
The method I use to clean them is pretty much the same as putting drops in. Fill the ear with the solution. Gently massage and then wipe out as much of the solutions as you can using a kleenex and/or cotton ball. I always like to wipe the outer ear with a cotton ball after applying medication drops as well, that way if he sticks his foot in his ear to clean it, he won’t end up getting liquid all over his foot. Sometimes when I have very thick drops to apply, I thoroughly saturate a Q-Tip with the drops and then gently dip it into his ear and massage.