The tree looks pretty rough and this didn't just occur overnight...or within the past year by the looks of it.
If it were that important of a tree, preventative is always better than reactive measure.
As a pine grows a limb up top, a bottom limb is sacrificed, so no limbs will ever regrow in the place of those already dead.
Your best option is to clear out the underbrush and thin out nearby trees and rid the area of unwanted/unneeded trees and growth.
Regardless, you are left with a stem with a heavy top susceptible to snapping off in the right condition.
