I was just about to suggest:

1. making sure the prey is thoroughly thawed and soft around the belly and head, reheating it in a zip lock bag in very warm water for a few minutes right before offering.

2. Ask for some dirty mouse bedding from the pet store (with mouse poop and all their heavy smells in it), and re-scenting the thawed mouse right before offering. I suggest heating it in a zip lock bag so that the mouse doesn't get wet + all the mouse bedding will stick to its fur.

And then I see Ax linked to my old thread. Hopefully this might work for you.