A 62-year-old female with bipolar I disorder, well controlled on lithium 900 mg daily and quetiapine 300 mg at bedtime for the past six years, presents for routine follow-up. Laboratory results reveal that her serum creatinine has risen from 1.1 mg/dL six months ago to 1.8 mg/dL, with an estimated GFR declining from 58 to 32 mL/min/1.73m2, consistent with stage 3b chronic kidney disease. Her lithium level is 1.1 mEq/L, which is at the upper end of the therapeutic range. Urinalysis shows isosthenuria with urine specific gravity of 1.005 across multiple samples. She is euthymic with no mood symptoms and denies polyuria or polydipsia. Nephrology consultation confirms lithium-associated nephropathy with nephrogenic diabetes insipidus and progressive chronic kidney disease. The PMHNP must plan medication adjustments while maintaining mood stability. Which planning approach is most appropriate?