Students who have not been formally diagnosed and more acquainted with their learning process probably won't think to ask themselves why they are having trouble remembering what they have read, or writing an organized paper. Generally, a student will probably give up on an activity before "assessing" exactly what the "trouble" is. It is your difficult job, then, to "dig around" in that student's process and access the areas that are causing problems.
You are also in the unique position of having the student practice strategies over and over again. Remember, in one semester you are not going to be able to "solve" all of this student's problems. You may need to focus on one or two strategies that the student can practice and employ for the rest of his or her life. Note that you will probably need to discuss your plans with the director of the Writing Center if there are requirements for how many drafts the student writes in the tutorial.