I'm on my first lager. I'll be bottling it in late Sept/early Oct and I don't plan on adding any extra yeast. I'm given to understand the amount of yeast left in suspension for a lager is comparable to that of an ale. I do agree that adding the yeast is easy insurance, so if it makes you feel safer, go ahead and add it. It certainly won't hurt anything. Also, I've heard some say that lagers take a week so longer to carb properly regardless of if you add yeast at bottling or not. Hope this helps.