If someone will be leaving their home before the time of bedikas chometz they must be "bodek" (check) the home for chometz in the same way they would check on the night of the 14th of Nissan. If a person did this anytime before the time of bedika and then the next day decided that they were going to stay in their house for Pesach, would they need a new bedika on the night of the 14th? Do they need to make a bracha when doing this bedika?
The reason perhaps they don't need at all is because a bedika was already made according to halacha and if they didn't bring any more chometz into their house perhaps then it wouldn't be needed. Or because they will be staying now in the home and should do things according to the way Chazal set it up, however maybe without a bracha since a bedika was technically made.