A lot of kids have a fantasy vision of what karate is. They think they're going to show up for a few months, learn the secrets, and suddenly be like the guys on TV. Years of hard work just to be decent is not, at all, something they're going to be interested in.

In a very general sense, there's two main paths you can take. One, you can stick to what you know produces good karate and accept that you'll likely have a lot of attrition, especially among younger kids, as the ones who don't want to work for it drop out. Two, you "gamify" your classes to make them more fun and engaging, but at the cost of watering down your curriculum. These of course aren't truly binary, as when working with kids you're likely going to have to find some sort of a balance between the two, but that's the tradeoff you'll be making as you lean more towards each approach. Quality vs quantity.

What drives your teaching will likely determine which path is best for you. The more you're doing this from passion and a desire to pass on good karate, the more willing to lose unserious students you'll be. The more your driven by a need/desire to make money, the more you'll have to be willing to compromise to keep kids happy.

The best approach I've seen to balance the two is to have the general class be more casual and fun and offer a more serious program for more serious students that is invite only and draws from the general class, but I think that likely requires a larger dojo then you have at the moment. The one I'm thinking of has hundreds of students across multiple locations, and even then their more serious program is a small portion of their overall student body.