When can you not use re as a prefix?

Answer 1

Re- is used to make a word mean "again" or "again and again" to indicate repetition, or with the meaning "back" or "backward" to indicate withdrawal or backward motion eg

regenerate; refurbish; retype; retrace; revert.

So if adding re to a word does not make the word have these meaning then don't use it. For example we can add re- to cough to make the word recough but recough is not a valid word

Answer 2

You should not use "re" as a prefix when the word that follows does not involve the idea of repetition or going back to a previous state or condition. Adding "re" to such words may create confusion or change the original meaning.