I'm actually surprised you got that much revenue with that site. It's missing two things: design and engagement.
Design - Looking at this site, I think most of your visitors can tell right away that it's not a serious site. It just doesn't look professional.
Engagement - This barebones site is missing soooo many of the engagement hooks that content sites use.
You're making this decision at the wrong point in the product's life. You haven't given it a fair chance yet. Building an awesome content-driven website is super tough work. There's a morsel of it here. Decide if you're willing to put a ton more work into this before pointing at your stats for decision-making, or if it's simply not worth the effort, for you, at this point in time.
Get in touch and let's have a chat. A few years ago, I built a recipe website, so I can give you a few pointers.
I agree that the design is amateurish, but I'm not convinced that's the limiting factor, so I'm reluctant to invest heavily in polishing it.
I'm not sure which type of engagement hooks you mean, but I don't see it so much like a standard content site like Buzzfeed or The Onion. I don't expect users to return every day to read the latest articles about which foods are keto. I think of it more like a reference site like IMDB where you go when you want to look up a particular thing.