She definitely deserve a chance! If that sick of leaves is not progressing, just keep do what you're doing 3 weeks, I guess. Plants that had problems at developing might grow longer.
But if you still have lack of nutrients, I'd suggest to add more secondary elements, like Zn, Fe, Mn, Mo. They usually contains in Micro nutrients with a lot of N.
CalMag is also a good idea, but I don't think it's the only and the main problem here.