It is never to late to return to nursing. Nursing is a vocation. It is part of you and you carry with you even if you are retired or take a respite to raise your children.
There are refresher courses in some areas. Look online and search for RN refresher course. Also you can take some CME courses in areas that you feel weak in.
When you go to apply for jobs, it may be difficult to start back in a hospital setting. However, office work is great if your want a more stable schedule and less demanding on an older nurse.
Good luck to you.
Nursing News