We often receive this question from customers, and unfortunately, the short answer is you don't. We don't have reliable or recommended process. Some customers have figured out a way by collecting on the new interface and tracking what file it's getting written to, stopping the IM service and replacing the new file with the old one. However, the integrity of the data can become compromised from this so it's not something we can support.
Data integrity for collected data is maintained by InterMapper controlling where the data it collects is put. Manual intervention by users saying "this interface is now this one" opens the door to user error regarding the actual data returned by probes. We don't let users add links between devices and expect to see data flows we don't discover and validate. It maps the network as discovered and monitored by the application, not in accordance with what the users believe they have.