This issue is not fully developed yet, but overall what is needed is the ability for the game creator to have multiple levels or scenes in their game. How this system would work exactly, I am not sure yet.
When the game creator wants a brand new level:
Information on the previous level should be stored, in case of returning back to it
A new level object (or class) would probably need to be created. This would store a new game window, and would have its own functions for when the scene first loads, and when it is repeatedly executing.
This issue is not fully developed yet, but overall what is needed is the ability for the game creator to have multiple levels or scenes in their game. How this system would work exactly, I am not sure yet.
When the game creator wants a brand new level: