Your CFAT (aptitude test) is valid for your entire career... UNLESS... you want to do a CT to a different trade, if you did not qualify for this trade when you wrote originally, you can re-write the CFAT to try for a higher score. Your recruiting centre will be able to find out that information. You are not privy to your marks, and never will be. But CFRC can get the test results and determine what you have qualified for. Keep in mind, that the most recent CFAT mark will be your mark on the books (or atleast thats what supposed to happen) so if the mark is higher, good job, but if its lower... its lower, and there is a certain waiting period before you can re-write the exam (I believe its three months, I could be wrong). But if you get a lower mark that is low enough to not qualify for your current trade, you won't be kicked out of that trade, there is ways around that, your recruiting centre will figure it all out for you.
As for your PT test, you will have to re-do that test, it must be current and must be done for your recruiting process. If you have done the express test recently, you will still have to do the PT test again for your recruiting process, its just the way it goes.
So short answers:
CFAT - no, you don't have to re-do it.
PT Test - yes, you will likely have to re-do it.
Hope this helps.