Reading code is almost always (much) harder then writing it. Learning you way around the existing code base, and refactoring it if necessary is (almost) always

Reading code is almost always (much) harder then writing it. Learning you way around the existing code base, and refactoring it if necessary is (almost) always a better option then rewriting it. In a rewrite you'll find your self relearning about edge cases already solved, you'll lose features and business requirements you didn't even know about. You'll end up with a more maintainable (for you) but worse product in most cases. Going forward you should have good documentation for key things regarding your system. If its not part of someone's job now, you should explain to your boss(es) why it needs to be someone's job in the future. Documentation is not time poorly spent.