Appreciate the replies--the "re-credit fee" seems to be the potential sticking point.

My ultimate goal for this trip is to use some expiring ANA miles to book seats in J--there's sporadic availability two weeks out for both NH and UA. (Although maybe not in May when I want to fly.) I'm planning to book refundable tickets as my Plan B in the event I can't book a late reward with the ANA miles. I'm okay with PE if that didn't happen (have a PE award on JL for the return, but need an outbound) and was hoping that if I put in for the upgrade and in the unlikely event it cleared a week or so in advance, I wouldn't be hosed if I cancelled.