As a business owner you cannot live in the past. What is done is done and you cannot change it. You need to look forward to make sure you don’t repeat the mistakes of the past and you are setting yourself up for the best future possible. Phrases like “We already spent so much money (or time or energy) on …” are a sign someone is stuck in the past. Those phrases are also irrelevant because that money, time, and energy are gone, never to return.
What you need to look at is what is best going forward. If Plan A is what you are currently going with and you realize Plan B is better, you need to switch to Plan B. Don’t let your attachment to the path you’ve been on stop you from changing to a better path if one arises.