It doesn't matter if you are in Canada or overseas. You will need to land. And that means you will need to enter the Canadian soil so the immigration office can process you as a new comer. You're already in Canada, I know, it doesn't make sense, I know, but this is how it's been for the longest time. Now I've heard they are trying to land people over the phone. Also if you can't get out and come back in you will need to arrange an in office landing. They will schedule an interview and you will land at a CIC office. But it consumes some time to schedule you in contrast with with the other option. (Although not sure about that now a days).
The procedure of getting out and coming back in (the other option), is called Flag Polling. You essentially drive to your closest border with USA which has an immigration office, you go into US soil, they hand you a paper, you come back and you get landed in Canada. Depending on when and which border you chose to go to, time varies from 20 mins to an hour. Just search for Flag Polling in this forum, and you get the grip.
Hope this helped, all the best and happy landing.