You can reload the scene you are already in with something like this (untested, but I know the general concept works):
get_tree().change_scene(get_tree().current_scene.filename)
If the code you need to reinitialize is in ready and you know when you need to reinitialize, you may just be able to do something like node_here._ready()
, which will call the function directly and it should run whatever code is there.
edit: One thing I should note though - reloading the scene using the snippet with get_tree
above will make the game seem to freeze for a second, as it reloads the scene. It is probably a good idea to use a transition/loading scene as a intermediate transition, like @cybereality suggested, to avoid the perceived game freeze/lag when reloading the scene.