Can't purchase more arrows
Solution 1:
Arrows will only respawn in shops if you have less than 50 arrows of that type (e.g. Normal, Fire, Bomb, etc).
As such, the best method to stock up on arrows from shops is to use up arrows until you have 49, then buy arrows from all the shops at once.
The only exception to this is Ancient Arrows
These will always be purchasable from Cherry at the Akkala Tech Lab