According to one of the KV-1's designers: "During 1942 we were still in need of a reliable heavy tank. That's why we were defeated in Crimea and at Kharkov. The KV-1 completely discredited the concept of a heavy tank".
Some Red Army high commanders demanded that all production of heavy tanks be stopped. Others suggested development of an "universal tank", something between heavy and medium tank. By the way, in the 1960's-1970's tank designers around the world came to the conclusion that it was the right decision.
Soviet tank builders tried to develop such a tank. This tank was named the KV-13. It contained many brilliant ideas (some of those ideas were applied in the JS-2 tank), however it never served in the Red Army.
At this time, a new decision was made to fully re-design KV-1. Soviet tank designers wanted to develop a new KV with lighter armor and higher speed and maneuvrability like T-34 Medium Tank. The new tank was named KV-1S where "s" letter means "skorostnoy" or "speed". The KV-1S was lighter than its predecessor by up to 5 tons. The thickness of the frontal armor was lowered from 90 mm to 75 mm. The rear hull was re-designed. The existing road wheels were replaced with newer, lighter ones. The KV-1's transmission was re-designed as well.
The old gear-box was replaced with a new one and the tank received a new turret with a commander's cupola (the first Soviet tank with a commander's cupola was T-50 Light Tank). Both ZIS-5 or F-34 tank guns could be mounted in this turret. In addition, the new tank was armed with four machine-guns: a coaxial MG, a bow MG, an AA machine-gun, and a MG in the rear of the turret. Also, new tracks (608 mm width) were designed specially for this tank.
In the summer of 1942, the KV-1S prototype was tested. On August 20, 1942, the production of this tank had begun. However, when the KV-1S appeared in the war theatre, the Red Army was already in need of a tank with thicker armor and better protection. A total of 1370 KV-1S were built. In April 1942 its production was cancelled. Many tanks were sent in tank brigades because the reorganization of the Red Army had not begun yet. The KV-1S took part in all major operations of the Red Army including Siege of Berlin.
Sources: "M-Hobby" #5-6 1997 V.Gagin "Heavy breakthrough tank Klim Virishilov" Poligraph 1996 "Bronekollektsiya" #1 1998 "Soviet heavy tanks in WWII" Tornado