When you lose a challenge

I have never viewed this game as a win or lose game. Now, if you're talking about taking up a Challenge, such as Pinstar's Legacy Challenge for instance. I totally blew it in Sims4, the first time. I forgot about the codicil that would have allowed me to choose my own Heir, even if they didn't fit the selection, I made up front. I chose a Trait he must have. After several babies were born, trying to achieve this, I had no other choice than to move out the firstborn son. (Rules are, the heir cannot move out of the house and still be the heir.) I could have simply decided he was the heir despite lacking the required trait. My bad. At first, I was going to roll back, if you will and take up things before, I moved him out and his parents were still alive. Or to just go back to their beginning. That's when I discovered the walk-Bys don't regenerate. I was devasted. I didn't attempt that Challenge for a full calendar year in RL.

ETA: That's before I understood how to recover a save, like we have now. Or maybe it didn't exist then. This was way, way back in 2014.

If this is what you're talking about, then I would have to choose: Stop and start all over.