Hard to say without knowing the plant name. I'd suggest trying a few that way as an experiment. Since the plant seems to be struggling hard, some pruning couldn't hurt.
Have you considered putting some cuttings into sharp, barely moist sand? Maybe with just a little sphagnum or coir or bark added to hold a little water?
Since it may well be very root-bound, maybe try a root-division as you re-pot it. Split some off when you re-pot it, and pot up the (small) split piece into a (bigger) pot.
