You are not going to get all of that money back for a long running show on here that has had tons of discount codes. Try stubhub or tiicketmaster re sale and hope you get your money back, but honestly you'll probably end up taking a hefty loss. You can also past date the ticket on a weekday after the performance.
Check out the app Todaytix if you haven't already for theatre tickets around the world. My referral code is DGHVR