A 68-year-old woman with a history of osteoporosis and a previous vertebral fracture is reviewed in clinic. She has been taking alendronic acid 70mg once weekly for the past 5 years. A recent DXA scan shows a T-score of -2.8 at the hip. She is post-menopausal and has no new symptoms. According to NICE guidelines, what is the most appropriate next step regarding her osteoporosis management?