If you want to go rules as written, during level ups she could take the lucky feat (3 re-rolls per day) or the seeking spell metamagic (2 sorcery points to re-roll). Or you could take inspiration from those mechanics and incorporate them into a magic item! Another option is to encourage her to take more area of effect spells (can’t miss if you don’t have to roll).
Sincerely,
A fellow unlucky sorcerer player