Why doesn't the air force order more F-22's?
Aside from Juan's point about the F-22 being fairly outdated by now (it's an 80's era design), it is also not possible to just restart production of it. 

First, it would cost ~$10Bn to simply get to a place where you can produce the an F-22 again. That doesn't include the actual cost of a single plane, just the money required to re-equip factories, train workers, produce a new engine since the old one is end-of-life, etc. Source

This estimate is assuming that the project was left off in the state Lockheed claimed it was. There is reason to believe that some of the tooling for the F-22 no longer exists at all. Source

Finally, the F-35 program has, in my opinion, shown that there is not so much to be saved by re-using components if the overall process is not efficient.