Treating dry skin. First and foremost, stay well hydrated. Lips tend to dry when you are significantly dehydrated. Second, make sure that avoid licking your lips as that may exacerbate the situation. If is possible to have rough/dry skin related to allergic, fungal, or other causes of dermatitis. Finally, if you are at risk for skin cancer (although unlikely at your age), the lip is not an uncommon location.
Find the cause. The first step should be to find the cause - it's possible that too much soap and cleaning can lead to rough skin, or sometimes too much moisture (for example, from repeated licking of the upper lip) can be the cause. Other skin problems may also be underlying causes. If this persists, a dermatologist may be able to help.