Hit the sponsors. Bans the team sponsors for a set period and have them indelibly linked to the drugs. You think that any company is going to drop masses of cash into a team that does not promote it's product in a positive light?
A switch of tact would be needed. Every official news source would need to read 'Saxo Bank drug cheat Contador banned from Tour', rather than omit the team name as it so often does now. Get that sponsor name front and centre.
I guarantee that the next round of negotiations would be something like;
"We'll pay £xx,xxx,xxx.xx up front, and the remaining 50% will be paid incrementally year on year for 5 years on the condition of no failed drug tests"
The teams need to be taking the stance on this. At the minute it's ass backwards. Teams need to be enforcing laws, not evading them. Make it in their interests to and they will.
If a team is 100% transparent it sends out a message. First up, they may 'lose out' for a few seasons as they will be running clean, but the team sponsor will be happy, if anything paying more to back a team, safe in the knowledge that it's reputation, and (due to the above financial clauses) financial interests are safer.
Over time this would surely send a message to young cyclists coming through the ranks that sure, they could go faster and dope their way to a pro team, but that they also have another route.
This change of tact could bring about a change in the sport. Riders coming through aspiring to be on a clean team, a clean team being rewarded financially for getting it's house in order, and ultimately, everyone sh1t scared of stepping out of line as they could lose their principle sponsor.
I know measures are being taken, some teams are already going above and beyond the call of duty, but the moment you hit the money, link them to drugs, ban sponsors for a set period... then things would get traction.
It would represent a sort of Panopticon of cleanliness.