As a general rule, Blue Spruce trees are not well adapted to the coastal plain of Maryland.  The high temperatures and high humidity of our summers are extremely stressful on these plants.  The stressed appearance of your Blue Spruce is evident on many other trees of the same species in our area.  The obvious signs of slow decline is evident in the sparsity of foliage and the tip browning of new foliage.  The tree may survive for several more years, but it may never regain its original beauty.  There are no specific treatments for the problem.  The only thing homeowners can do is to provide the tree with supplemental irrigation during hot, dry periods.  And, actually, it would be appropriate to provide such supplemental irrigation through the fall, up until the ground freezes.  Cold, dry winter winds demand adequate soil moisture in order to maintain the viability of the needles.
LS

Thank you so much for your clear, thorough response!