1. download the application form and fill up - that will save you time and $4/form.
2. get your handsome picture taken - 2 will do, to be safe bring 4. if don't have, there is instant passport photo machine in the high comm.
3. be at the high comm first thing in the morning. morning is to submit application for passport renewal.
4. within the same day's afternoon can collect passport.
don't bother getting it done in Jb. No guarantee can be ready within the same day.