Priming with additional yeast

I am brewing a lager that is currently in the lagering phase around 35 degrees. I am bottle conditioning this batch in a few weeks. I assume there will not be enough yeast and/or it won't be strong enough to build the carbonation I want. I plan to add back some yeast with the priming sugar. I already have the yeast saved from the primary that I washed.

My question is: With the additional yeast, how do determine the correct amount of priming sugar to add? Wouldn't be the same amount? Also, if I am making a starter with the left-over yeast, would I calculate the exact amount of sugar (DME) for priming and just use that for the starter?

Thanks! and sorry for the lengthy question

Me I would just use the about the same amount for a 5 gal batch around a cup of dextrose. The fact that the yeast is new vs still in the beer doesnt change the amount of sugar needed IMO.