My mother is 101. Apart from sight and hearing and Osteoporosis her only condition is low sodium levels 120-127. Any advice?

My mother 101 was admitted to the hospital 2 years ago when her sodium level dropped to 119 and she was on a drip for days. This was caused by her being on water tablets for too long- she really didn’t need them but her prescription hadn’t been checked over the years. For two years after that her levels were fairly regularly checked and she was okay but low. Now she has been in and out of the hospital three times in 5 weeks with low sodium levels ranging from 122- 127. The only thing offered was reduced fluids which has been difficult in the hot weather. She has been told that she must now live with these low levels and the symptoms because this is her norm. I’m wondering if anyone has advice on how to cope with this. Having been fit and active she’s now weak and drowsy and sometimes a little confused, all because of the low sodium.