Cost to extend a Fix/Flip loan with private lender?

[Whitney Hutten]

Hi All, I have a fix/flip loan on a SFR that is maturing at 6 months come May. I had it under contract and it fell out late in the game for a very silly reason. It's reasonable to assume it will close in the next 60-90 days. I notified the lender that I'll need to extend. He's requiring an additional 1.875% penalty fee ADDED to the balance of the loan (essentially increasing the IO payment every month, which means it's more like a 3% increase). What is a reasonable fee to charge? I could refinance into a bridge for this amount... How have others handled this issue? Thoughts?