Start again! There may be things you have forgotten or overlooked. Starting again gives you an opportunity to catch what you might have missed.
One of the most famous mathematicians in the world, Andrew Wiles, said that one of the most important things he did was forgetting that he had failed with one approach before, so he tried it again, giving it a new chance.
You may not know who Andrew Wiles is, but he solved one of the greatest problems in math. It is called “Fermat’s Last Theorem”. It took 358 years before someone solved this problem. Imagine trying to work on a problem for 358 years without giving up! I’m sure you can spend one hour on homework. As you can see, it can be smart to start again.