I bought a ticket in M class econony standard for 10,000 hkd, ticket expire dec 30, 2015 (I already flew the first leg)
There is a high probability that I cant use the second leg by dec 30 but I need the same flights for Jan 30, 2016.

Below is the fare rules
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Rebooking

Free of Charge. Fare difference may apply
Cancellation Fee

Before departure: TWD2400
After departure: TWD2400
Stopover

Stopover Hong Kong:
2 stop(s) permitted. On the outbound journey free of charge. On the return journey free of charge.
Note

There may be other charges associated with stopover ie. Taxes.
Stopovers must be "en route" during the journey; conditions from the fare rules apply.
Mileage Accrual

You can accrue Asia Miles on this fare.
Upgrade with Miles

Permitted
Pre-book Seat

Permitted
No Show Charge

If you do not turn up for your flight there is no penalty

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What are my options?

Should i pay TWD 2400 and get a refund? If i do opt for this option would my refund by 5,000hkd or something less?

Can I upgrade to H class and extend the ticket for another half a year say June 30, 2016? or to J or PEY so long as i can extend the ticket by 1 month