There is a limited update when the maximum score changes. That is the WeChall points are recalculated based on the old user score and the new maximum.
However, Yoire reports a percentage as score, so the maximum score will always be 100%, making such a recalculation useless.
We do not update all user scores, because this is almost a DOS attack on the site with the current API.
One solution could be to ignore the reported score and just use the number of solved challenges as the score instead.