Hydration/electrolytes - When not training

I am new to the longer distance tris, and slowly working through my nutrition/hydration needs while training. My question is more about the time between training sessions. I am wondering if I am restoring those electrolites to prepare me for the next session.

I drink a good amount of water during my day (80 - 100 oz, not including during exercise), but not much else besides the water. I believe that drinking just water during exercise can also have an adverse affect on electrolytes. So is it possible that I am not "recharging" those electrolytes between sessions?

To make matters worse, I am a heavy salt sweater. The kind of guy that has crusty white helmet straps and look like I was playing at a white sand beach after a good hot weather work out. Do you all include added electrolytes (ie Endurolytes) between training sessions?

Thanks,
Eric