Drop in supply

I’ve been breastfeeding for almost 7 months with no problem with supply. I would pump in the morning, so I would have a stash when I went back to work. Shortly after returning to work I decided staying home worked better for my family. I slowly began pumping less often. My LO has began eating solids. Tonight was the first night I had to feed her a bottle of expressed milk after nursing because she was still hungry before bed. I think I may have been a little dehydrated today. If I drink more water will my supply return? Any other tips? I really would like to make it to a year without supplementing.