Me and my friend had a fight?!?

Me and my BFFF who lives next door have been arguing alot. I need help on what to do because i'm starting to think that we are not BFFF's (Best Female Friends Forever) any more. Im 11 and she is 10. Some arguments are stupid ones and others are ones that really effect each other. I need advice on what to do. I was going to throw her a surprise party for being a friend abut this will be the third time it got rescheduled.