Refundable tickets are often no longer refundable on the day of travel -- they have a clause for a "no show" charge and require cancellation 24 hours ahead ... so check the terms carefully. Time of year affects the answer, both for likelihood of delays SFO-AKL (isn't UA suspending that flight for the next 6 months or so?) and delays into ZQN. Only safe way is to allow overnight in AKL on separate tickets, otherwise normally 2 hours is sufficient connecting time and 3 hours max.