If it is done correctly, fixing a cracked windshield that has a small star will not make it crack any further. Indeed, it will halt the cracking process. To do this, a professional will take a small tool, after cleaning the windshield, and drill down into the layers of the laminated glass (windshields are made of laminated material). When the tool reaches a depth of good glass, the technician removes it and injects some epoxy which dries and then buffs the windshield. It has been restored to good condition, although there will be an obvious mark on the windshield. If the windshield is physically cracked and the crack is growing, it must be replaced.
For more info, see How to Fix a Windshield that Has Been Cracked