Use a humidifier. Chapped lips are lacking moisture and during the wintertime, indoor heating can make dryness even worse. Moreover, many people sleep with thier mouth open, which further dries out the lips.
Humidifiers return moisture to the environment, lessening the lack of humidity that contributes to dryness.
Lick the lips. While saliva provides immediate moisture, the effect is only temporary and actually dries the lips even more once the saliva is dry.
Licking the lips removes the skin's natural lipids and makes it difficult for them to retain moisture.