I don't think the spruce will ever be what it should have been. I'm assuming
it's a dwarf or you wouldn't have planted so close to a building. The soil
surrounding buildings is typically very basic from the lime that leaches
from motar and cinder block and the building material trash buried during
construction.This is not very good for many evergreens.
Cut out the dead part. The bottom looks healthy enough. It may develop
several leaders to take over for the dead one. If not, it will probably just
grow in a spreading fashion and not grow a lot taller. Definately not good
as a foundation plant. I'd try a new one further from the foundation or
check out some plants that like that situation more.
Gary