To repent, one must give rise to the mind of repentance. That is
most important.
One can also recite the following verses (with the repentant
mind):
All the evil karma that I have committed in the past,
Arising from my aeons of greed, anger and ignorance,
Committed by my body, speech and mind,
Now I repent before the Buddha.
But without a repentant mind, whatever one recites doesn't mean
there is 'repentance'.
http://www.jenchen.org.sg/vol6no2c.htm