obmanuti

1. to deceive; to delude
   Obmanuo je birače lažnim obećanjima. — He deceived the voters with false promises.
   Ne daj da te obmanu lepe reči. — Don't let pretty words deceive you.
2. (obmanuti se) to delude oneself; to be mistaken
   Obmanuo sam se misleći da će se promeniti. — I deluded myself thinking he would change.

The imperfective is obmanjivati; the word is more formal than prevariti.