It is possible to change the lock on a deadbolt without replacing the entire deadbolt. It is easy, less expensive and requires less effort. You may want to rekey a lock for security reasons or possibly to change all the locks around your home to use the same key.
Rekeying a lock is a basic task performed by any locksmith. You could hire a locksmith to come to your home and rekey your locks, but you can save a lot of money if you bring the cylinders in to a locksmith's store and have the work done there.
To remove the cylinder, remove the screws from the interior face plate of the lock. Separate the inner and outer sections of the lock. At this point you can carry the half with the keyhole to locksmith. If you remove the cylinder from the housing you risk loosing the small pieces contained inside the cylinder.
If you intend to key all the locks in your home alike, you should bring all the cylinders in at the same time. While this isn't absolutely necessary, it is much more convenient than making repeated trips with different sets of cylinders.
After the locksmith has rekeyed the lock, simply install the outer section. Align the inner half of the lock with outer part, make sure the latch is set to the unlocked position and fasten the two halves together with original screws. Now, test the deadbolt and test the new key.