How recent should the English language certificate be to apply for Master thesis?
Yes there is an expiration limit on these language tests. 

I believe most tests are valid for 2 years. I know for instance that the TOEFL test has a 2 year expiration date. Unfortunately, I do not have any experience with the CPE test, but I have personally never heard of any standardized test being valid for more than 5 years. 

I would suggest you retake the test. That being said, you should contact the program you are applying to directly to get the most information about what tests are/are not accepted and for how long they are valid after taking them.