Chapped lips are an extremely common but sometimes very frustrating medical problem that can be difficult to clear up.
Most of the time, chapped lips are not caused by any serious medical problem. Rather, they occur because of chronic irritation and dryness of the lips, most commonly by repeated picked and licking of the lips. This is a problem, because the discomfort of the chapped sensation often triggers a repeated cycle of habitually licking and moistening the lips. A major part of getting the lips to heal is figuring out a way to break this cycle. As you have already mentioned, various chap sticks are the first line treatment, because they keep the lips moisturized. It is helpful to get a chap stick that has a menthol or other cooling agent in it, because this will reduce the irritating sensation that provoke lip licking.
Also it would be helpful to see your primary care doctor
, especially since this has been going on for such a long time. They will be able to examine your lips to make sure there is not another problem going on that needs additional treatment. For example, if the chapping is mostly at the corners of the mouth, this might be a condition called angular cheilitis, and not chapped lips at all, which would require a distinct medical treatment.