I would think add water until it comes on. I'm considering buying a secondary pump with a battery just in case. Seems like, when you need it most, the power goes out.
Mine went out on this past Christmas Eve. Picked a new one up at Lowe's right before they closed that night. It was melting that day, and if it had been 5 degrees warmer, my basement would have been toast.
I was told you have to have the right size sp for your basement. Too small, they run too much and burn out. Too big, they don't run enough, and can develop a flat spot (not sure where that would be).
I have heard the best back up option is a water pump. You actually run water through this manual pump from an indoor water source into the well, but the water drives the pump and it pumps water out faster than the water coming in. That way you don't have to worry about a power source for the backup. Not sure how you engage the water system though, I'm sure it's automatic. I think they are pretty expensive installed. $500-$700 ?