Increasing sentences is a common knee-jerk reaction to these kinds of things, but it doesn't usually play out the way people think. Humans are complex, and longer sentences usually result in higher crime rates in society. Which seems to defeat the point.
I think a better solution would be to develop some kind of RICO Act-like legislation, with various changes to avoid some of the strange ways it's been used in the US. The RICO Act destroyed the Mob's stranglehold on America, and has been used successfully to eliminate gangs and other criminal organisations since.
Essentially it would be a law that allows leaders of criminal gangs to be charged with the actions of its members, or a prohibition on being a leader of a gang. These kinds of laws allow the police to simply establish someone is the leader then put them in jail. When they are inevitably replaced, the next leader is taken out too. As this continues, being the next leader will be very unattractive, and with the good leaders gone, the organisation falls to pieces.