The question, howerer was how many times you "should" say it, as in how many times it is required, and that would be only once in my oppinion. Nothing wrong with saying it more often if ya feel like it.

Someone told me a story about a couple who had been married for 30 years, but the husband never told the wife he loved her. One day she was fed up and confronted him about it, and he replied "I told you I loved you when we got married. If I change my mind I'll let you know."