obmanjivati

1. (+ acc.) to deceive; to mislead
   Političari godinama obmanjuju građane. — Politicians have been deceiving citizens for years.
   Ta reklama obmanjuje kupce. — That ad misleads customers.
2. (obmanjivati se) to delude oneself; to fool oneself
   Prestani da se obmanjuješ, on se neće vratiti. — Stop fooling yourself, he's not coming back.

The perfective is obmanuti; the word is somewhat formal, and in conversation people more often say lagati or varati.