Rack carefully as to not stir up any sediment, and rack onto your priming sugar mix. There will be enough yeast in suspension to get the job done for you. 70* or more for 3 weeks, and youll be good to go!
I use 2oz with good success. I boil a couple ounces of water and add the dextrose to that. Then dump the sugar/water mixture into the keg, seal with CO2 and purge O2. Wait 2 weeks at room temp ~72 put in fridge and consume!