first aid for half dead arborvitae
potted half dead arborvitae can you re-pot and trim the dead off? can you do anything to help them? do not believe in the pitch and replace all the time
Arborvitae, along with many other commonly-grown conifers, generally don't produce fresh growth from "old" wood. So unfortunately, I would not expect the dead portions of the canopy that have no foliage to produce new shoots and leaves. The portions of the canopy that have foliage will continue to grow.
If you plant out this shrub you can place the dead area to the back.