1.
(Active.) Continue, maintain, keep up, push forward.
2.
(Neuter.) Cling, stick, hold fast, keep hold of.
3.
(Neuter.) Continue, remain, endure, last.
4.
Persevere, persist, be steady, be steadfast, be constant, go on, keep on, keep one's course, keep or maintain one's ground, stick to it, not give it up, stand fast, stand firm.