Hi pundarisandeep,
Do you know which Schools in Canada you specifically want to apply to? If you do, then you should be able to research the individual Programs and get a better sense of whether your 540 is competitive-enough to apply. Even if you don't know which Schools you want to apply to yet, then you should still do some research into your options. The process of applying to (and ultimately attending) Business School is a big investment of time, money and energy on your part, so you really need to make sure that you're applying to Programs that fit YOUR goals.
If you end up deciding to retake the GMAT, with the goal of scoring higher, taking more CATs is NOT really the solution. To improve your scores, you have to learn (and practice) new tactics and build up your overall skills.
1) How long did you study?
2) What materials did you use?
3) What were the Quant and Verbal Scaled Scores on your Official GMAT?
GMAT assassins aren't born, they're made,
Rich