Maybe try a post-it note to help him remember? I honestly do not have a degree in beardie psychology so I don't know why Lilly doesn't get out from under her rock. Sometimes I wonder if she is just being soooo lazy that mommy has to help her out, or if the first few days she was hiding from fear and I got her in a routine so she waits for me to pull her out. Maybe she even knows that she'll get a snuggle before I put her back in to bask. I do know that once she's out, she's out for the day.
Do I understand correctly that you are using both a 100w and a 150w in a 40 gallon tank? Do you have them both dimmed down VERY low? I'm wondering because a 75 w keeps my 36 gallon plenty warm.
I can suggest a few other minor improvements to your husbandry. First, I think beardies are supposed to be between 6 and 8" from the bulb. I doubted that it would make a difference, but with my boyfriend's beardie, he lost his appetite when he was moved farther from the UVB and then it came back when we got him 3" or so closer. That being said, I really don't know if 4-5" is too close and could be bothering him. They can be such finicky creatures lol.
Second, if you're misting, do it outside of the tank. Doing it inside raises humidity too much. Just to give you an idea, Lilly's poos will raise humidity by close to 20% until I can get them cleaned up! I try to
bathe every other day, although sometimes it is every third day depending on work schedule. Hope this helps,
Sara