What preventions can I use to help decrease asthma attacks in kids aged 7?

Identify triggers. Try to avoid exposure to triggers. These may be weather change or change in levels of humidity, air pollution, smoke, dust, etc or to common respiratory viruses or emotional or stressful situations. It's important to classify the type of asthma and to treat accordingly. Most of the time a child with frequent attacks needs chronic treatmwnt with iinhaled steroids and bronchodilators.
Triggers, meds. First you need to determine what might be triggering the asthma attacks. In kids, allergies are a very common trigger so a visit to an allergist is important. There are good medications that can help prevent asthma attacks, too. Your allergist can help you figure out which is right for your child.