My R1150RT did exactly that, having the clock reset, a few days before the battery got so low it wouldn't start, which was thankfully at home and not out on the road.
From my experience, you need a new battery.
Exactly my experience too with my '04 RT-P, only I wanted to see if a long ride would charge the battery so off I went. Then I suddenly got stuck in a stop and go traffic jam after some yahoo flipped his SUV. And I got tired and stalled it. And yes, it wouldn't restart. I pushed it and got off the highway and rested at the exit. Pushed it a couple blocks to a slight downhill and pushed started it and came right home. Exhausted.