Why was the return rejected. You are correct, re-filing the same info won't help; you need to correct whatever the issue is that caused it to reject. Filing as a full year resident won't cause a reject, there is another problem. Was there a reject code? You should have received an email that provides some details on the reason.
How to file a part-year return. This will help you fix your residency dates, but I suspect that this is not why your return was rejected.