If Gorbachev had correctly diagnosed the Soviet Union's problems and realized that political reforms would be a disaster he could have:
Ended the Cold War and accepted that the Soviets weren't going to push the Americans back in the world. Cut off the overextended Soviet positions. Cut back heavily on the armed forces, relying on the nuclear weapons to keep the country safe. This would have saved huge amounts of money
In Eastern Europe, he needed to cut back on the independence of the satellites states by gaining control over the various armies. This could have been done by choking off their supplies particularly oil.
Economic reforms of decentralization and restoring the price mechanism could have done wonders
Above all, don't let the political system decentralize and open up. This destruction of the Soviet Union was inevitable once that process started