specifically for altcoins, it is worth notifying the exchanges where the altcoin is traded that you were hacked, providing the address where the coins were sent to (by the hacker) and convincing evidence that the coins are indeed yours (and were stolen from you).

Then the exchanges may block the coins if they already received them - and might eventually even return them to you.

I say specifically for altcoins  since for most of the alts there's pretty much nothing else to do with them apart from keeping them or sending to an exchange - i.e. no good ways of laundring.