do you have an open work permit? PGWP? did you have an LMO when you first applied for a work permit?
usually if you are a foreign worker with a contract and your employer wants to extend or renew your contract, they need to apply for a new LMO. you need to attach the positive LMO together with your new contract and apply for a work permit extension at least 1 month before it expires. when you send the WP extension, you need to send it in such a way that you will have a signature proof of delivery. once received by the case processing center, usually Vegreville in Alberta you will be on implied status until they make a decision on your case.
if you do not intend to renew or extend your work permit, you can stay as long as your temporary residence/visitor visa is valid. but keep in mind, if your work permit expires without you applying for an extension, you are not allowed to work.