If you have to pay $75 to change the ticket, you'd be better off buying the ticket outright and saving the miles (assuming you can find a cheap way to extend them). For June, one ways OGG-LIH are around $100-$110.

If you really want the non-stop, I'd find a way to extend the expiration of the miles and wait to see if you can get the non-stop or buy the ticket outright if you really don't want the stop in HNL.