If your baby is now a preschooler, I would assume that most of your plastic needs replacing to make sure it is safe. With my first child, I bought all expensive Advent bottles and he wouldn't touch them (preferred cheap playtex), so I always advise to buy only one or two of few different kinds of bottles and nipples and then only stock up on what your baby likes later. And both my breastfed babies liked different nipples. Go figure.
I bought new bottles for my Medela anyway, because the old ones were pretty worn. Make sure you disinfect (boil) all the attachments and tubes as well because bacteria can linger, even when out of use for a while.
Otherwise, all I can advise is go easy on yourself and what you can do. Two is harder than one and it's not as easy to get the sleep you need when you have an active child at home. Also, if you are breastfeeding, your toddler can be a huge distraction. I was very anti-TV with my first, but didn't hesitate throwing on a cartoon to help get me some quiet time to nurse baby #2.
Good luck to you and congratulations on your growing family!