Put your current story on hiatus and start your new one. At some point, you will come up with an idea for your current story which will make it so much better than if you keep going with only a half-assed attempt, and you will feel better about it because you created the best story that you could. Don't force yourself to stick with one story just because you don't want to leave it half finished, because sometimes it takes a break from writing something to come up with a new and fantastic idea.