Yes, if it meets your needs and you still enjoy owning it. You could still be using this one for years with the occasional minor repair, even if you have the 'bad' engine. A car of any age or price can surprise you with an expensive repair, and with this one's value in disposable territory it's easier to walk away from if it came to that. Or, who knows, you might still be smitten with it and decide it's worth the trouble.
But since you're asking the question, you may already have a reason to move on.