I was looking into this a while back when I was sending my update letters. I know you are looking for a sample, but I would like to mention: Your update letter does not have to be like the one posted above. Many applicants' letters are short and to the point. For example, you can list your grades (paragraph format is fine), mention any new activities, and give a few sentences expressing your interest in the school. There are no hard and fast rules about these letters and they are, of course, not required or necessary if you do not have any substantial updates.