How do I modify a level in its own editor and make it global?

Hello everyone, I have a question for you. To start off, I’ve created an editor for my game; it works well, though it isn't quite finished yet. Currently, I handle JSON exports by compressing everything into a list of characters—an approach that was actually suggested to me. I decided to build this editor to save valuable time and make level creation easier. Anyway, here is my question: how can I create a level using this editor directly within the game, without going through an export process? In other words, how do I permanently save the created level and integrate it into the game? I’d like to resolve this issue before moving forward; otherwise, I’d be forced to program the levels line by line, which would take a huge amount of time. Thanks for your help!