I've done it both ways- not added yeast, and added yeast. The batches without added yeast eventually did carb up, but I was unsure for a long time!
Anytime I lager for more than about 4 weeks, I now add yeast before bottling. You don't need much- maybe 1/4 package of nottingham. What I did was boil up the priming solution, cool it, and then pour it into the bottling bucket. I added 1/4 package of dry yeast, and stirred that well. It started "blooming" right away, and I siphoned the beer into it as usual.
That works great! You don't get extra yeast sediment (just about the same amount you'd normally get) and it ensures enough viable yeast to bottle carb. That was especially helpful when I had an extremely clear maibock. It had an OG in the high 1.060s, and was lagered for about 9-10 weeks.
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