If you don't have other children to save that money for, then the Military Family Tax Relief Act gives that 529 money all back to you penalty-free minus taxes on the gains. You can use it for
whatever you want: vacations, new cars, hookers and beer...
It's just your money at that point.
We have one child. We kept the 529 in the account until he graduated in case anything happened along the way, and then we rolled it all over into our retirement portfolio. Another approach is to withdraw it at the same rate you would be paying for college, one quarter each year in two installments. The point is to make sure it's available in case your mid/cadet ends leaving the academy and needs it for civilian college.