You can give freeze-dried treats throughout the day for treats. Not sure what you mean by them being "rich"? Do you mean they are too expensive? I could give you links for some lower cost ones...
Is she underweight? What canned foods are you giving her and how many times a day are you feeding her? If she needs to gain weight, a higher calorie canned food would be more effective for weight gain then giving her kibble. I could give you a few suggestions Or, you could increase the number of calories she's getting with the canned food she's currently eating by increasing the number of meals.
Congrats on getting your second test!!!!

Testing starts out hard, but you'll become a pro at it in no time. Bandit had me in tears when we first started testing, he was so difficult. 9 years later, he sits and purrs through the whole test like nothing's even happening.