GMAT is not the only thing important in a B'School application. But when you are applying to any B'School you need to know about the competition you will be facing during the application in your geography and field. With your work experience you will get an admit if you applied 4-5 years ago but today the competition is high. If you are planning for the top B'Schools, you need to improve your score. But you can check out with the B'Schools regarding the score range which they admit and decide about what to do

GMAT score depends on B-school and also the field you want to go into.
Also other factors like work-ex, GPA, resume also count
Check out the requirements for the b-School you want to apply for and decide whether to retake

Unless you are shooting for scholarship/fellowships or trying to get into top 20-30 program, score of 660 should be good enough for the majority of business schools. Check the avg GMAT score of the programs you are applying to and see where you are, you might want to retake if you fall towards the lower end. I'd probably spend more time trying to beef up the rest of my app ex: resume, recommendation letters, essays, etc