Frazer, I put so much effort into my youth group, as much as the other leaders. Each one of our hearts desires is to see the youth worship God in spirit and in truth. We all put in x amount of hours a week: 95% grit, and 5% glory. If I have to die for 5% glory, I will, just to see the youth lift their hands in worship.
We havent seen a breakthrough in worship yet, we're just trusting God. Most of the churched kids do not join in praise and worship either.
When we get the breakthrough, we'll baptise them. Until then, its just a faith walk: We cant make them worship God! Its their choice.
As for your situation, maybe take them away for a weekend (this is the closest we've had to a breakthrough), and just teach them on worship: maybe start at the basics, why jesus died, how horific his death was, and thats why we should worship him.
Also, read Matt Redmans story behind the song "Heart of Worship." Its awesome, someone mentioned on here, I researched it, and I was glad that I had. Heres the link.
God Bless, metal.