Well, I don't think I will be having anyone redo their sheets if the stat costs are raised, I think a better option would be to have them make up the difference in X amount of time ( 2-3 months ) so long as they pay a certain amount each update. Which I think is the most fair way to do it. It allows them to keep their purcahse and in this instance allow them to keep updating as long as they are making the effort of making up the difference.
Right now it's looking like it will probably end up putting the soft cap at 13, hard cap at 18 with a much higher cost for going over 13, and raising the cost of stats in XP as well.
Really, the sheet redo's was an unfortunate hassle, and one that I hope to avoid in the future if at all possible. Since we were so early in the game it wasn't much of a loss and it's not like anyone had to correct for a year worth of updates either.