It is up you to you what you choose to do. Personally, I do not feel it is necessary to retake science classes that I have already taken years ago. Especially if you have already been working as a nurse for so many years. Your clinical experience, your new RN nursing classes and clinicals will give you the education necessary to become a successful RN. Especially with the nursing shortage right now, they should not be deterring prospective students who are already nurses. They should be welcoming any and all students, with experience, who wish to stay in this field. Best of luck.