I have always understood this topic to mean that Jesus took his blood, and once and for all eternity offered it on the mercy seat in heaven. Not that he continues to do so, or that he lays prostrate praying for us 24/7, but that the offering stretches forth to cover all of time. The intercession being made is that offering that continues to be there available for all who would come, hence His Priesthood continues through his one time offering.