Swaping between scenes without repeting code

[NUGA]

When designing a game, at some point we will have to switch to another scene (level, main menu whatever). A way to do this is every level, for example, will be a scene. When the time to change scenes comes, just change them. However some code, at least the way i'm doing, reapeats: input handler in the update, score texts, etc. So i wonder if there is a better way of structuring the code in way that this won't happen?