Back in the 90's I received my Tech license. I let it expire. Now many years later and I have the time (Retired) I would like to get back into Ham Radio. Do I need to take the Tech exam again? Or If I show proof that I took the test and received a tech license I can just pay any fees and be reissued a tech license?
You must retake the examination. The relevant regulation is §97.505. Unfortunately it is formatted in a table which I can't quote in full neatly, but the relevant part says:
(a) The administering VEs must give credit as specified below to an examinee holding any of the following license grants:
(3) Technician Plus; or Technician granted on or after March 21, 1987
Expired and beyond the renewal grace period
(b) The administering VEs must give credit to an examinee holding a CSCE for each element the CSCE indicates the examinee passed within the previous 365 days.
On the other hand, if you had held a higher class of license, you would be able to regain your license at that class by only taking the Technician exam.
Note that in any case you will also be assigned a new call sign. If you want your old call sign and it is still available, then you may apply for it as a vanity call sign; this can only be done after you have your new call sign.
Look at it this way: you have time, and you need to take the exam. You might as well shoot for Extra along the way! Get studying!