You don’t need to install a new door, or even a doorknob if you want a better lock for you home. All it really takes is a good lock cylinder, and a locksmith can help you out.
The quality of your lock is, for the most part, dictated by the cylinder within. Modern locks have long been built with cylinders installed within the system. As a result, a locksmith can get into the lock, remove the cylinder and replace it with a high-quality solution relatively easily. This allows you to upgrade your lock without necessarily having to make a major investment.
While you can make a basic lock upgrade with just a bit of help from a locksmith, you may also want to look into more expansive options for lock services. One key consideration is a combination of dead bolts and similar secondary locks that reinforces the system and makes it less dependent on a standard locking device.
Reinforcing the door is another option. Even the strongest locks may not help you if the frame around the door is relatively weak. Reinforcing the door can provide a vital layer of protection that, when combined with an upgraded cylinder and new dead bolt, could provide a vital layer of protection.