Ok, seems Charm can be refreshed in the PvP servers because
you're allowed to cast offensive spells (like charm) on pets
and PCs. So on the PvP servers, you can recharm your pet
while it's still charmed. On the non-PvP servers, you try to
recharm your pet, it's protected, so you have to wait for the
charm to expire before recharming. You might want to make a
note of this in the song analysis, Rokenn.