Basically the cause for chronic hiccups
,in your father,seems to be due to uncontrolled diabetes
,uremia,hyponatremia ,hypokalemia since he is suffering from chronic kidney failure.
Ideally all the metabolic deficiencies should be corrected and this should lead to normalization of hiccups.
The best medicine for chronic hiccups is chlorpromazine
which corrects more than 80% cases
Some times haloperidol is also used.
In severe cases intravenous lidocaine has also been tried.
In very severe
cases ,not responding to medicines,Microvascular decompression of vagus nerve or surgical interruption of phrenic nerve