When your mortgage is coming up to the end of it's term (a.k.a. maturity date), unless you have the means to pay off the remaining balance in full, you're going to need to renew your mortgage for another term.
At the end of a mortgage term, you have several different options:
1. Renew With The Same Lender
Anywhere from 3-6 months prior to your mortgage maturity date, the Lender you currently have your mortgage with will be in contact with you to discuss your renewal options.
Depending on your Lender, they may call you to discuss by phone, send you an email or mail you a letter which outlines your options, or they may contact you to book an in-person meeting.
Your Lender is going to try to make it really easy for you to renew your mortgage with the hopes that you'll just agree to renew your mortgage with them without shopping around first. The convenience is nice but your Lender may not be offering you the best deal on your mortgage. There may be better options out there.