Since lower level of potassium is 3.5 you are getting worried I think. If she doesn't have signs of hypokalemia that is low potassium like muscle twitching muscle weakness abnormal heart rhythm nothing to worry. Repeat potassium after a week along with renal function test.
Next Steps
wait for a week if no symptoms of hypokalemia and repeat rft and potassium after a week
Health Tips
give her tender coconut and banana rich natural sources of potassium