DS1's lips chap frequently. We've gotten in the habit of having him put Vaseline on his lips every night right after brushing his teeth before bed. His lips have gotten much better. It seems more effective for him to prevent it by applying it daily than trying to fix it after it gets bad. Once you get this cleared up, you may want to try something similar.
Typos courtesy of my "smart" phone.
Hi! I'm Shannon
Wife to J
Mama to a couple of crazy boys - L (12/07)
and E (2/11)
and Meatball coming 4/14