I do think the updated exported preset file should replace the old one.
That is only if it has the same name, if it doesn't then you need to go to your Feral Heart>Exports folder and manually delete the file.
It should display the time and date that the file was moved into the folder on the right side, so that should help you find it.
Also, I suggest creating a help thread next time you need help. It can give you a bigger variety of answers to your question and stuff. ^.^
Anyway hope I helped you, floof.