http://www.cic.gc.ca/english/work/apply-how.asp
If your work permit has expired before you have submitted an application to extend it, you must apply for a new work permit to restore your status within 90 days of the expiry date. With your new work permit application, you may have to submit a copy of a positive Labour Market Opinion (LMO), a document your new future employer must obtain before he can hire you. The restoration of your status through a new work permit requires that you pay the $150 application fee.

It is illegal to work in Canada without a valid work permit. If you do not extend your work permit or apply for a new work permit, you will be without status and you will have to leave Canada.

Are there any conditions on my work permit?

Your work permit may limit:

the type of work you can do,
the employer you can work for,
where you can work, and
how long you can work.

Все зависит от вашей рабочей визы, если она мульти то нет проблем если однаразовая вы не можете покинуть Канаду и вернутся опять на работу