Yes you should take her back.
If it is an asthma related cough she might need steroids to clear it up. I can have a cough for months and unless i get a steroid inhaler it will not go away.

The other thing to be aware of with ventolin is that there is a school of thought that you should try and give it as little as possible to children as their lungs can become dependent on it. I have it for both girls, but i try not to give it unless they are either having problems sleeping due to the cough or obviously if their breathing is labored.