Dig a new planting hole where you intend to move the shrub before you dig it up. When you do dig up the plant, sever the roots around it by driving a shovel all the way around it — 12" to 15" from the center of the shrub. Then angle the shovel sharply to get to the roots directly beneath it, and begin cutting them as well.
Water the transplanted shrub well, and don't let the soil dry out. Apply a 3"- to 4"-layer of mulch around the base of the shrub.