Hello,
Application for any work permit renewal is done on paper and sent by mail. For PGWP renewal, you should mail it to : Case processing centre in Edmonton. Immigration refugees and citizenship Canada. C/o work permits/new employer, station 555, 9700 Jasper Avenue NW, Suite 55, Edmonton, AB T5J 4C3. It's always good to use a tracking number to know whether your mail was delivered. Then you should try to link your paper application to your online CIC account. You will be able to do that one month or 2 months later. Thereafter, you can receive all correspondence about your application through your cic account. Hope I answered your questions. Good luck.