I would retake the ACT. There is no denying that scores are important at ND and by retaking the test there is the possibility that you can improve your score. In last year’s cycle, ND denied well over half their early applicants, and given A) a test score below the 25th percentile, B) a decent but low by ND standards GPA, C) no hook, and D) strong but fairly garden variety EC’s, anything you can do to improve is important. With a month and a half to prepare, you would give yourself a fighter’s chance of improving a point or two, which could tip the scales in your favor. Both of my daughters applied EA and were deferred, but fortunately accepted RD. As someone who knows how special ND is, I would hate for you to be denied not having done everything you can to get in. Best of luck!