What "Ri" in front of a verb means in Italian?

When you see RI attached to any verb in Italian, it simply means repeating the action described by the verb.

Eamples:

FARE = TO DO

RIFARE = TO DO AGAIN 

MANGIARE = TO EAT

RIMANGIARE = TO EAT AGAIN 

STUDIARE = TO STUDY

RISTUDIARE = TO STUDY AGAIN

It is that simple!!! :)

Ciao e a presto!