There exist SAT and ACT tutors who fill out a form after the test outlining for parents why the student didn't get the score they wanted. I think it's a CYA thing, and I can see the motivation, but it seems a bit mean. However, if I DID fill out such a form, "Doesn't read enough" would be one of the check-boxes. "Didn't do what I told him to" would be another, and for many students this would amount to the same thing.
Students (and their parents) are told the importance of reading over and over again. We all know we should be reading, but many people -- teenagers in particular -- don't. Even if a student is a big reader, sometimes they don't read a wide enough variety of texts. How many times have you heard, "They can read ANYTHING! It doesn't matter! Find something they enjoy!" This is only true up to a point. When it comes to college readiness, the ability to read non-fiction at a college level is crucial. However, you can't count on colleges to teach the student how to do this. They expect their students to arrive already reading at a college level. In fact, college entrance exams are specifically intended to measure the ability to do this. High schools haven't traditionally done such a great job either. They tend to focus on the types of fictional reading the practice of which will come in handy if you major in English Lit. The Common Core Standards are supposed to address this issue. We'll see.
When I get a student who needs work in the reading section, I usually assign reading homework. I send home articles that were written "for grownups." The students get to choose what to take home, although I encourage them to choose articles on topics they know little about rather than articles they think they would enjoy. This is the homework that is least likely to get done. I'm not sure why. Is it because they can't bring themselves to read "boring" stuff? Is it because they don't see the immediate connection between the assignment and improving their test scores? Is it because the improvement is not as immediate or obvious?
An aside-- If you are reading this, and you are one of my current students: I can tell when you didn't really read the article. I may have chosen not to embarrass you, but I know.
Usually when a child's reading score is low, it's because he really doesn't read all that well. You can't fix that without reading. So, READ, dangit!
Check back tomorrow for some specific reading suggestions.