Applying protective paraffin-based ointment (such as Vaseline) or lip balms
to the
lips is normally very effective. Also take Vitamin B supplements.
If nothing works you can have a biopsy done to find out the cause.
ref:http://en.wikipedia.org/wiki/Chapped_lips
Some causes of the symptoms you mention, could be lip biting, lip licking, Vit.B2 deficiency, smoking, overexposure to sun and ill fitting dentures. In extreme cases, this could be due to bacterial or fungal skin infection.