My wife has a hard time turning the Revoshift grip on her Electra Townie 7D due to arthritis issues in her hands. Is there a way to help with this issue?
After a while all shifters get a bit harder to work due to the cables drying out of lubrication, getting dirt in them and the cable strands oxidising. Replace the cable - both inner and outer - and you may get silky smooth shifting again. This could do the trick.
As @thajigisup says, go to a shop and find the shifter that works best for her. 'Old fashioned' top-mount levers might not be in the shop but they are definitely a consideration.
More generally I am very disappointed by the exceptionally conservative bike trade that only allows mainstream sports-fad products of zero innovation level to get into showrooms. Shimano have created several groupsets with electric push button gears for the recreational market and even tried to get a fully automatic gear system accepted by those manufacturers that are stuck in tradition dictated by the UCI governing body for cycle sport. Fair play to Electra for creating some bikes with geometry that suits non-racers, however, they could do with focusing a bit more on functionality, to make bikes that do suit those who do have small hands with arthritis like my own mum.
Maybe get something that will work for now, e.g. new cable plus track-mitts might provide the easy-leverage. Research the cool electric components that Shimano do offer, beg your distributor to get them or source them from the Netherlands (one of the few markets for such parts). Then, maybe for Christmas or a birthday, deck your wife's bike out with ultimate luxury electric gearing. You will enjoy the project and be able to share your experience of putting it all together with others that don't suit the tired race only geometry offered by most of the trade.
Everyone on these forums is going to end up with arthritis or worse one day, pioneer the technology for the rest of us so we get better than a choice of zimmer frames in our old age.
I recommend getting a rear Shimano trigger shifter. This would mean getting both a trigger shifter and a grip because I think your current grip is designed for the Revoshift shifter.
The part I'd recommend for this use is the shimano acera 7-speed trigger shifter, which costs about $15, if you're in the US.
If you are mechanically inclined, it's pretty easy to do the work yourself, and it's a lot of fun when you get it working.
If you're not mechanically inclined, bring it to your LBS to install. This will save you the effort, and you eliminate the chance of irritating your wife for breaking her bike.