If she did well on Nature's Domain Turkey and Sweet Potato you can continue to feed it. Nature's Domain Grain-free is ok food. It's a tad high on carbs (a tad low on protein) for my choice, but I'm on the high-protein fan club.
Note though that Nature's Domain (Kirtland Signature) is a Diamond product and they've been through some recalls (always bad mark on a dog food company) so pay attention to the recall announcements to determine which lot numbers to avoid. The Turkey formula has not been recalled to my knowledge, but the Salmon and Sweet Potato formula was voluntarily recalled for any bags that has a "Best Before" date of Jan 3, 2013.
If you can find a good quality food with Turkey and Sweet Potato ingredients then it might be worth looking into. Fromm Four-Stars has a Duck and Sweet Potato recipe that might be good to try.
Hope this helps.