Someone who is having difficulty to find something out, after strugling a lot with no success, needs a fresh pair of eyes to assist them. So to complete the sentence with the appropriate idiom, we can finish with "What it really needs is a fresh pair of eyes" <em>(another person to examine closely in addition to anyone previously.)</em>
Your audience would be the teacher or whoever is grading you, because the purpose of a critical analysis as to examine your point of you of the topic and how you structure of the essay based off of your opinions and possibly facts
