Other people here have a lot more experience than me so maybe one of them can chime in. But what you describe, and she's old enough, sound like 'spring fever'. Mine are all over their cages, right now.. they'll 'wreck' their setup - shoving hides and water dishes around and upturning their bedding.
I have read of snakes having a color preference in their mice, but never heard it directly from an owner, but it's certainly possible. Do you feed in a separate container? If it has black/dark sides, the mouse might blend in more, but you say she picks it up, then drops it (distracted?) So she has no problem finding it.
You don't have any boy snakes around now, that you didn't before, do you? If she smells a male, and it's 'spring' that might also be changing her behavior.
You could try warming up the food more than normal ? (close or more than 'live' temperature may make them more appealing -just don't cook them!!) Have you tried to wiggle it with tongs and tease her with a little to get her to strike it? (as she latches on, continue to wiggle it a little to keep her focused on 'killing' it until she wraps around it.
If she's in otherwise good health and weight (which I"m sure she is) missing a meal now and then won't hurt her. But I'd be worried just like you if it were mine. Everything else has been good? Normal poops?
I don't know if this would work, but the next time she refuses, give her a few days then try giving her a long handling session just before you feed.. Drape her around your neck, have her crawl along your arms and generally get her moving around a lot.. She'll be getting warmed up good from your body heat and the activity may stir up her metabolism and appetite.