Chevy hasn't tweaked the Bolt EV much since its introduction, but an impending refresh could be welcome by giving drivers what they often crave: more range. The EPA has rated the 2020 Bolt EV as delivering 259 miles of range, up substantially from the 238 miles you've seen since the start. As Car and Driver observed, that would give it greater longevity than the Tesla Model 3's Standard Range Plus trim (240 miles), the Kia Niro EV (239 miles) and the Hyundai Kona Electric (just shy at 258 miles).
It's not certain just how Chevy wrung out that extra 21 miles of driving, but C&D understood that new battery chemistry was the key.
Don't expect a drastically upgraded car beyond that. The Bolt order guide only makes reference to new color and minor feature options. If you're not fond of the design, this won't change your mind. Having said that, added range could be enough of a selling point by itself. It can make the difference between having to recharge mid-route and making a non-stop trip, and that could reel in buyers who'd either look at other EVs or (gasp) consider a gas-powered car instead.