I got her ages back when the DLC was released and have leveled her to 12 currently but what i want to know is whether you can find out what you gave her to level up and whether you can reset her to level 1 in anyway shape or form or is she stuck at that stat once its happened.
You can't reset. You can always get another crystal. You can't figure out exactly what you leveled her with since there are too many permutations for that to be reasonable but it's easy to check whether or not you've optimized her.
I always had the impression, that you can get every monster only once, unless you sacrifice or release it. Then you can get a second one. But I believe you have no other choice but to receive another 5-star-rank for the Reqiuem-DLC.
The only way is to try it for yourself.
Though Commander-Lightning is still a game breaker, even if not optimized.