The price I paid for 2 tickets from Honolulu to San Diego have dropped by almost $300 each. Since they are the 2nd part of a round trip, Alaska Air told me I'm not eligible for a refund for the price difference on that leg of the trip. Is there a way I can work around this?

If the terms of your ticket require a change fee that's larger than the price difference, you'll get no refund rebooking for the lower fare.

You could keep hammering at Alaska Air; be persistent. Some airlines will give you a credit for the difference you can use later, which to me isn't hugely beneficial, but it's something.

I doubt it. Airline pricing is dynamic; a given class of seat on a given flight can cost many different prices, based on what the airline perceives market demand to be at the time of sale of any given seat. That said, nobody knows what the market will do in the future, so the airline risks selling for too little, just as the customer risks paying too much. Look on the bright side: the airline can't work around the price it got from you, should market demand for your flight suddenly soar and they find that they could have sold your seat for much more to somebody else.

I agree with Sue_xx_yy!