Hi Jyoti,
If you have changed the length of any field in datasource structure level and replicated it after transport, then the transformation will get deactivated and they will expect the old field lengths which are not there anymore after transport.
As Raman said you will have to move the activated datasource and transformation/DTPs into Prod again.
However, if there are no absolute any changes in structure of datasource and your changes are solely to source system and its logic in Function Module then I think the transfomations should not get deactivated.
Please let us know if any of the above cases are true.
Thanks
Amit