I've seen mod videos on YouTube of Runner owners that have added a 7-speed freewheel to their bikes but it sounded like a lot of work to get it done and I've only seen it done with a different hub motor added. I have a Runner Plus and, as Tacomanatx mentioned, I almost 100% of the time ride in only 1 gear regardless. Though I live in a mostly flat area with only minor hills now and again.
Otherwise, I'd say a 35amp controller upgrade would give you the extra torque to get up the hills instead if you need it.
Otherwise, I'd say a 35amp controller upgrade would give you the extra torque to get up the hills instead if you need it.