godan verb (-su), transitive verb
top up; replenish
Used for adding liquid or granular substances to a container to restore the original level, such as topping up a drink, refilling a water tank, or adding more rice to a bowl.
お茶を注ぎ足してください。
Please top up the tea.
ご飯が少なくなったので、炊飯器に
The rice was running low, so I added more rice to the rice cooker.