Keep cost low at SOAP service version update

Some of my collegues and I were discussing today what the correct term is when you switch from one Version of an interface to another.

We have another company who has an Soap webservice. They switched/updated their service from one version to another, but the changes are so drastic that you have to reimplement 60% of the code that accesses the SOAP webservice.

1. is there a design pattern which helps you keep the work at a minimum level if such an update happens ?
2. if you know how to do it then you probably know what the correct term is for that kind of implementation, is it reengeneering or refactoring or what ?