Choosing "Start from 0.1.3" automatically assigns your character the name "non" and there seems to be no option to change it available. For those who just want to play the update without starting over, I would guess the easiest way to do this would be to choose Start from 0.1.3, make a save, and use a save editor of some sort to change the MC's name?
EDIT: Yep, this method works. The save files for FlirtyF are in the "C:\Users\YOURUSERNAMEHERE\AppData\LocalLow\OppaiComics\FlirtyF" directory (make sure to replace YOURUSERNAMEHERE with whatever your user name is on your PC XD). Choose Start from 0.1.3 and immediately make a save. I used
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to edit the save, just drag and drop the save file from the save directory into the browser window where you have the save editor open, then CTRL+F to search for "playername" and you'll see that it is "non" in the save file. Just replace it with whatever you want your character to be called, remember to keep the quotation marks, then scroll down to the bottom of the page, download your save file, and replace it.