如何更改iPhone应用程序中的版本号

I have an app approved by app store that is version 1.0, and I want to update the app to version 2.0. I changed version to 2.0 in iTunes. It's in the "waitin for upload" state. I have made some code modification in my version 1.0 and changed the bundle version as 2.0. When I am about to upload the appbinary using xcode, it still shows the version as 1.0. If I m to click the validate button, it gives a message that it's already uploaded. Should I change the bundle identifier? I'd be so grateful if you guys could help me out.I have an app approved by app store that is ver