Firstly, please post messages in English because everyone here cannot read/understand Kannada and using English as the official language for posting messages is the forum's rule.
Ya coming to the matter, channels buy rights for a particular time say 5-10 years or even more (especially among South Indian languages). Once the agreement between the channel and production company ends, the production company gives another chance to renew the movie's rights. If the channel is interested to keep the movie with them, then they will renew it again. If not, the production company sells the rights to another network (channel).