I will be at WDW for more than the number of days I have park hopper tickets for. I'm thinking of switching my park day that I already have reserved FP for but don't want to lose what I already have in case the day that I want to switch to doesn't have availability. When I go online, I can't search for FP on the new day because it says my FP limit has been reached. Is there a way around this or do I have to cancel my existing FP for the old day first?