hmm. I repaired my watch a few times but the activity app data was still in there. I don't think I reset it though. Reset wipes it? I don't mind wiping it and starting over personally.
Unfortunately Im not sure there is. There have been a few other threads on here where people have stated that unpairing and repairing the watch and restoring from backup results in some loss of activity info.
I have the modular face with Date, Calendar, Weather, Activity and Battery complications. Been off charger for 8 hours and I'm at 87% still. Have always made it the full day with about 50% left.