I left my XR on the charger for 10 days while I was away, without any change, but I can try leaving it plugged in all the time.
My XR is dying less than 1km from home, so I can add some air to the tire, turn back sooner (which I hate to do), walk up the giant hill it's surging on near the end of the ride, or just take it a little easier (which I also hate to do). App says my top speed is 32.5km/h (20.2mph) so I'm probably pushing it beyond what's "safe" anyway. (but isn't that half the fun?)
I might try that swap option Lia mentioned or just wait for a new model, which I'll undoubtedly feel compelled to buy (I have a OW, OW+, OW+XR). This XR has 1600km, which isn't huge but it's bearings are getting a bit loud too..
Anyway - thanks for the advice! Happy riding!