New Construction Exceeding 12month build term

[J Hart]

Currently building a new home and due to a variety of pandemic, supply and weather related delays (we’re in the mountains), it’s exceeding the 12-month build window on my construction-to-permanent loan. Original rate is 3.375% from closing last August, but obviously now with current rates 2x higher, the lender did a 3-month extension at the original rate but is going to take the whole thing up to market rate after that. Builder will be close to completed by that point but not entirely. The difference in interest rates on the ~$400k financing would be nearly $900/month more than original plan. Obviously trying to avoid this at all costs!

Besides pushing the builder to complete as fast as possible (which is already desperately underway), are there any other options to exercise with the lender, or advice on how to squeeze another month extension with the original rate? Thank you!