Once the timer bar ends, there are two possible outcomes.
The Timer Bar Will Hide
This is the most common behavior. When the timer bar counts down to 0, it will be hidden immediately.
If the timer bar is set to appear again in a future time window—for example a "Recurring daily" type timer bar—it will show up again when a visitor lands on your store during that time. Once the countdown reaches 0 again, the bar will be hidden just like before.
Note: When you update a campaign and then save and publish it, your customers will see the updated campaign again.
The Timer Bar Will Reset
When you're using the "Fixed duration" schedule type and the "Reset at end" option is turned on, the timer will reset and start counting down again each time it ends.