--responding to @needs native check--
should be "keep up"
yes; it should be "keep up"
I unlinked the last translation that was linked to this sentence. I would say that this sentence can now be deleted because the existing sentence "Keep up the good work!" ( http://tatoeba.org/eng/sentences/show/567757 ) carries all the meaning that was intended here, and is correct. Another alternative would be to change the meaning of this sentence so that it effectively becomes a new sentence.