Originally Posted by
Shareholder
Your only hope is to keep checking back with AE to see if any business class seats open up on your return, then grab it.
Another option that a competent AE agent can do is put you on NZ's waitlist for Business award space. (This was possible, and succeeded, in 2007 at least).
Originally Posted by
Shareholder
However, you could try to insist on being put into the Premium Economy cabin on the return.
This is a strategy accessible to every other passenger ticketed in economy. It's not likely to be successful.