To truly eradicate a cockroach infestation, you must take a comprehensive approach to pest control.
First, you must seal off their access to your home. This means aggressively filling every tiny crack and crevice in your home with silicon caulk. Start in the kitchen and bathrooms and pay special attention to the spaces around water pipes and drains. Seal the insides of your kitchen cabinets and along all of the wall trim. This can take many hours, but will really pay off.
Next, clear up the clutter to take away their places to live. Get rid of paper and boxes and clean up clutter.