Hi, when you apply for extension of your study permit online, you don't need to upload a copy of your study permit. So as long as you know your client ID number (8 digits) and the expiry date of your study permit (probably same date your visa expires), you can apply for extension. CIC has your information in the system, so you don't need to worry about your lost study permit. Just apply for extension before it expires or you will lose your status.