Answer:
Persist, persevere, continue, carry on, go on, keep at it, keep on, keep going, keep it up, not give up, be persistent, be determined, see/follow something through, show determination, press on/ahead, plod on, plough on, stay with something, not take no for an answer;
be tenacious, be pertinacious, insist, be patient, be diligent, stand one's ground,stand fast/firm, hold on, hold out, go the distance, stay the course, grind away,struggle on, hammer away, stop at nothing, leave no stone unturned;
informal:
plug away, peg away, stick at it,soldier on, hang on, stick to one's guns,stick it out, hang in there, bash on.
