On the off chance that your guest visa terminated and you have to leave and come back to Canada, you have to apply for another guest visa. Much of the time, you should apply online to broaden your stay as a guest.
If you do not have much savings or other income this can be a problem, but there is the option to include an affidavit from a friend or family, who is a permanent resident or Canadian citizen, in which that person assures that they will cover their expenses while you stay in Canada. This person must also include a letter of employment and a copy of the last Notice of Assessment (tax) to prove that they have the compulsory income from an extra expense.
If you genuinely wants to extend your VISA then you have to apply at least 30 days before your current work permit expires.
In most cases, online applications are accepted to extend your VISA
How Online application can help you: