API Gateway Deployment issue

I am trying to deploy api gateway using serverless framework in AWS environment and my api definition are written in swagger file. I have different stages within that api gateway. When i first run the script all my stages and deployment works fine. When i update my api definition and re run the deployment to only particular stage, the deployment is not getting updated in the stage area,but when i do it via console manually things are working fine. Can some one please help me here knowing the exact reason why such behavior is occurring and what should i do to get this work.
If any other solution over aws cli please suggest!!
Thanks in advanced