I don't RP in the style you do, I mostly just do it over IMs, but I know what you mean. Unfortunately there isn't a quick fix to that. :\ If they're not original characters, sometimes watching an episode that is centered around them helps. Or writing drabbles... or doing some intense RPing with the character that's fading. OR making a CD of music that reminds you of them and listening to it nonstop. XD