The mod stores most of its data in an external ini file which doesn't come with the mod files but instead is created automatically once you run the game and register your first character.
You can edit this file at your will but do note that this is considered cheating to Dead Is Dead challenge so it's advised to only edit when you need it.
Also note that wrong edits can break the mod's functionality, though it's always possible to completely reset everything by deleting the file.

The file name/location is ...path to game folder\Data\Config\h-z's did charlist.ini.
If you're using mod manager this file can be located somewhere else, you may check "Overwrite" folder or something along the lines (I don't have much experience with mod managers, sorry).

Once you've located the file, open it with a text editor of your choice, standard Windows Notepad will do but something that can highlight ini syntax (Notepad++) will make editing it easier.
The contents are pretty easy to read if you ever edited an ini, you have the name of character in square brackets  (as section) and consequently some individual parameters for each character/section.

It would look like this:

[Character Name]
iLives=3
bLevelsEqualsMoreLives=1
bLENukaGivesLives=1
iDeaths=1

Everything is pretty straightforward, right?

iLives is amount of lives you've chosen for your character at the start. You can manually set this to any positive number up to 9000. Anything higher than 9000 in considered as infinite lives.

bLevelsEqualsMoreLives is "Nth Wind" feature toggle, a feature that makes it so each even numbered player level gives an additional life. Set it to 1 to enable, set it to 0 or remove the line completely to disable. You may not have this line if you haven't initially enabled this feature for this particular character, so you may need to add it manually.

bLENukaGivesLives is "Nuka Saves The Day" feature toggle, a feature that makes it so consuming limited edition nuka cola gives you additional lives. Set it to 1 to enable, set it to 0 or remove the line completely to disable. You may not have this line if you haven't initially enabled this feature for this particular character, so you may need to add it manually.
Note that the amount of LE Nuka you've drank is always tracked, independently of this feature state.

iDeaths is amount of times your character has died. If this higher or equal to iLives, this character is considered dead for good, unless you have enabled additional features from the above - then it will evaluate character's level and amount of nuka consumed when you load the save and add it to total amount to lives, which may still allow you to keep going.
You may reduce it, set it to 0 or remove it completely to resurrect a dead character, of course this is considered cheating. But you may as well open the console and type "togglegodmode", it's your choice if you want to play against the rules.
You may not have this line if this character haven't died a single time.

That's it, one last trick is that if you want to completely reset the mod for a particular character you can remove the whole section OR (recommended) just set amount of lives to 0, then next time you load the game with this character the mod will reset itself and welcome you with "Time to play The Game" dialogue again.