I get my brushes fully wet before putting any paint on them, then blot some water out of the tip before you load it. This will help keep it from sucking the water out of the paint. You can also drip a bit of water on the bare fibers with a blunt needle squeeze bottle every now and then, up above where you are loading the paint to keep it wet without having to dip it in water.
As for more spring, try a synthetic bristle brush intended for oils / acrylics. It will not go limp with the water like a natural hog bristle brush will and will give you a lot more spring than watercolor brushes.