You can always cut your mesh in half and duplicate the good side and then connect the two good sides together. I never duplicate anything until its done or I need to make somethin asymetrical. If you're not done, using a smooth proxy should avoid these problems.
"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
George Bernard Shaw - Man and Superman