This question already has an answer here:
To my knowledge temporarily abandoning the ISS is one of the possible options. (Though not the most probable one.)
If left peopleless, how long can it stay in orbit without proper maintainance and still be available to return operational?
What are the main systems that require crew's constant attention?
P.S. Soviet Salut-7 space station was once abandoned and returned in operation afterwards. What are the key differences between the current possible ISS situation and that with Salut?