What options are there for a cleric to permanently gain extra uses of a domain ability normally usable a number of times per day equal to 3 + their Wisdom modifier, aside from alternate favored class bonuses?
The Believer's Boon feat can give you 1 use of that ability, but it's pretty limited. That feat is not really meant for Clerics, but it still works.
If your character is Mythic, there is the Mythic Domain path ability for Hierophants. This will allow you to spend a mythic point once a day to regain all your domain power usages.