That's simply not true.
Go to this "Bible Gateway" search for "repent" in the "Revised Standard Version Catholic Edition" of the Bible, and you will find it returns 115 instances of the word "repent", with roughly half in the Old Testament, and half in the New Testament.
(The "Revised Standard Version Catholic Edition" of the Bible is likely the most widely used English version of the Bible by Catholics today.)
Now, do likewise in the Douay-Rheims which has been so heavily touted by RC partisans here on Free Republic.
What does it say?
“Do penance.”