I kept dreaming of my ex even though the break up was like 2 years ago. Sometimes he just shows up in my dreams. I dont know if you believe in stuff like that but depending on what you dream it can tell a lot about you. http://www.dreammoods.com/dreamdictionary/e2.htm on this site you an check what it means to dream about your ex. I hope it helps :)
I believe that dreams are a way of somehow foreseeing the future. I dreamt of my ex 3x for this month. He left me 6 months ago. I was bothered by his repetitive appearance in my dream only to find out that a week after the last dream, we were destined to cross paths again. It may not be the same for you but your mind is sending you signals. There may be an impending scenario where the both of you will be involved or just the human nature of missing someone you used to be close with. Either way, I suggest you do not give the dream a high importance.