You can go back by two thirds the size of each branch and your Pieris will resprout and look great. Just wait until early spring such as March and try to leave a few branches unpruned until next year. If you shorten by two thirds but leave one third of the branches alone the shrub will forgive you and grow again. I happen to love the foliage of Pieris so don't waste it after you prune. It does great as evergreen filler in windowboxes or in a vase to bring inside and enjoy for a few weeks. There are also some dwarf Pieris in case you want to replant the monsters with some better behaved and more compact cousins. Keep growing, Marianne Binetti