It's a weird issue. I have refactored the interaction model of my existing skill in the development version. I renamed the intents and slot names. The changes are reflected and working perfectly in the simulator but on echo dot, it recognizes the old intents and slots which are available in the production version.
Finally able to resolve the issue.
As I was updating only the Interaction model of the en-IN region, and my device was configured with en-US, the old interaction model of en-US model was creating the mess. after updating the interaction model of all region. its working now.