There's a great deal of responsibility that goes along with applying to college. Remind your senior that the responsibility is theirs for getting and completing applications, following instructions, submitting teacher recommendation requests in a timely manner, meeting deadlines, and keeping all appropriate people informed of their situation. 

You can help them by establishing a convenient place in your home for their college files, and setting a time once a week (perhaps on Sunday evenings) to talk with them about the progress of their college application process.