What can I use to clean the smell of urine from my hardwood floor, so my puppy won't want to go there anymore?

I got a puppy almost a week ago. I am working at getting him housebroken. But he still has accidents here and there. I'm using lemon scented household cleaner and it doesn't leave a smell that I can tell, but I know that he can probably smell where he went and it makes him want to go there again.