First and foremost, one should have a job offer to stand eligible to apply for Canadian immigration as a skilled worker. If you have a job offer, then you can apply once per a valid job offer. There is no restriction on the number of times you apply but one must wait before applying again. One would require to have another separate valid offer of employment to apply again.

In case, once the application is rejected the likelihood of it getting accepted becomes lesser the second time. The cutoff for acceptance is a minimum of 67 points out of 100 and the job offer bags for a maximum of 10 points.