Pricing is an art not a science. It isn't, and frankly cannot be, cost plus a reasonable profit.
The magic price for anything is what the punters are prepard to pay. Charge anything more, you spill customers. Charge anything less and you have lost an opportunity. Figure out the maximum that they will pay, deduct all the government fees and charges, and what is left is your fare. And customers are prepared to pay more on thin and/or monopoly routes.
If you drop your fare 10% you need to increase your pax count by 10% just to break even. If you halve your prices you need to more than double your pax count. This just isn't going to happen on thin routes like this.