Definitely retake. When you take practice tests, remember to study the questions you got wrong and teach yourself WHY they were wrong. This will help you improve your score.
Your ACT is below average for your target school so why wouldn’t you re-take it? I would also suggest that you consider 1) taking a review course 2) getting a tutor to work with your on the English section, or 3)buying an ACT prep book and practice on your own (to include going over mistakes and understanding your errors, taking timed practice tests etc.). https://www.cmich.edu/admissions/undergrad/incoming/Pages/admissions_criteria.aspx