Well I dont know about restarting, but I was stuck in the exact same part that you were, heres how I beat her after 3 months of being stuck

1. I used limit brakes alot, mostly ivrine and his ultimate ammo. did a huge amount of damage on her.
2. I used alot of hero's like 4, and just cast triple on squal, then had him cast curaga when I needed it.


that worked great for me