Partial Refund for Miles-redemption upgrades

I am premier gold. I have a flight on 12/21 from LGA --> DEN--> SJC. I was offered 20k Miles to redeem upgrade up to FC. Given the craziness of holiday travel, seems like a no brainer.

Quick question- I was automatically cleared from Den --> SJC. I am wait-listed on the LGA --> DEN flight. If my upgrade doesn't clear for this flight, do I get refunded portion of the 20k Miles back?

Thanks for your response in advance.