I brewed a lager and I have been lagering it for a couple of week now and it’s really clear. My question is do I have to get some yeast back into suspension or is there always enough to naturally carb in bottles?
I’d recommend “swirling” a bit of yeast slurry into the bottling bucket to insure proper natural carbonation. No worries! 
No need to do anything. Even though it’s clear there will be plenty of yeast left in suspension after just a few weeks to carb up the bottles.
There will be plenty of yeast in invisible suspention.