Translation
And if that house is indeed deserving, let your peace come upon it; however, if it is not deserving, let your peace return to you.
Paraphrase
And if that house proves to be a wholesome place (full of peace), let your [desire for greater] peace come to fruition in it; however, if it proves to not be a wholesome place after all, let your desire for peace return to you [unfulfilled].