Ah, sorry, I misunderstood. If the business needs change, re-evaluate the business case. Does it still stack up - is it still worth doing the project? If yes, continue. If no, execute a controlled close and shut the project early. That's the main consideration, but you could also look at what can be "saved" from your work to date, and repurpose it, or put the project on hold if the expectation is that the business needs will change again in the future and the project will once more be required.
