Upvote:1
Nothing related to obtaining a visa or granted entry is entirely safe. Unless you have other issues you haven't mentioned, have not already graduated, etc you will be allowed entry. Make sure you have all your documents in order to present at the airport if requested.
http://www.cic.gc.ca/english/study/study-extend.asp
If you want to extend your stay in Canada as a student, you must apply before the expiry date on your study permit. Complete the Application to Change Conditions or Extend Your Stay in Canada. You should apply for renewal at least 30 days before your current permit expires.