I often hear this.

Problem:
This is either a mispronunciation or an unnecessary invention.

Explanation:
Some people know the verb “occur” and assume that the repeat form of it should be pronounced “reoccur”; this is wrong.

Other people know the verb “occur” and assume that they must invent “reoccur” as the repeat form of it; this is wrong.

The correct verb — “recur” — already exists (and has no “oc” sound within it).

Wondering whether this speech problem also occurred in writing on the Web, I searched Google for “reoccur” and “recur” and got about 455,000 and 3,800,000 matches, respectively. That tells me that Web authors have written the word correctly by a ratio of 8.35:1, which is okay. And, because the most popular “reoccur” matches returned by Google talk about why this is a misspelling / mispronunciation of “recur”, the ratio of correct use to incorrect use probably is higher.

Solution:
“Recur”