I have lived in Canada from September 2010-May 2014, and have been a PR holder since September 2011. From May 2014-December 2014, I moved to Pakistan and then came back to Canada from January 2015-April 2015. I have now been in Pakistan from April 2015 till date. My PR card is valid till October 2016, and I want to renew it. What is the best way to go about it, and when should I visit Canada to do so?