Yes, less nitrogen means more sugar going to the buds among other things. The last 2 weeks of a grow I use Jacks Finish 7-15-30 at 1/2 strength and MOAB 0-52-32 or Chi Ching 9-50-10 also at 1/2 strength. 

At the end they will start pulling the N out of the leaves if they need it like Rick said. If the leaves start turning yellow too soon you can always add more but you cant extract the N.