How to use "File->New" to create a new (duplicate) window of current form

I’ve found the Qt documentation for QFileDialog and similar things, but all the references I’ve found discuss opening existing files or saving your current file. I haven’t found anything that states how to actually create a new file, i.e. a new instance of your application.

I’m creating a character record sheet for a game. Since it’s possible for one person to have multiple characters, especially if the game master wants to have many NPCs, having the ability to use File->New Character would be useful.

In summary, if the application is open with a character sheet, how would I call the code to create a new character sheet? I am using PyQt5 and the character sheet is created w/ QtDesigner.