When I start my game again the destroyed turrets are still not there

I have already finished my game, everything is working. I have a Start Scene, where I can Quit or Start the game. When all turrets are destroyed it goes back to this main screen, but when I hit the Start-Button again, the game starts, but the destroyed turrets are not there anymore.

Is there any script that loads the level new, or it also would work if the whole game starts new