If you can, store the rinsed pump in the fridge between pumpings. And give it a hot soapy wash (and a sterilize if you want to) once a day. Just let the syringe get to room temp (only take a few minutes) and then give it to her - you don't heat the wind drops! When there is more she may prefer it warmed up - cold won't hurt her, she just might not drink it as well.