You mean like a platformer where when you go back you see another environment?
So because I don't know what you want here are just a few thoughts.
If it should happen at a certain stage then I would try it with an invisible hitbox.
So when objPlayer goes back you just check with another condition if the hitbox is now gone or set a variable.
If you want it all the time - then I would try to create or set the new environment visible as soon as it is e.g. 100px outside of my window . And at the same time destroy the old one (or set invisible).