Wow! This is the first time I've read someone wanting them to go down from being up. Most of the time, it's the other way around.. lol. I have a 4 month old girl whose ears are floppy and I've been working on them to stand and we're having no luck..I think she's gonna be a floppy eared yorkie...wanna trade?
Seriously though, I've never heard of them going down after being up other than when they're still young and/or teething. Since he's 6 months old, I don't think they'll go back down but maybe someone else knows more about that..