Practitioners know that amendments to pleadings are liberally allowed. But every now and then, they are denied. What can you do then?
An order denying leave to amend is not directly appealable. So that's out.
You could try your case on the existing complaint and appeal if you are unsuccessful. But in that case, it would be difficult to establish any error in denying leave was prejudicial – after all, the trier of fact rejected your evidence.
There's always a writ petition. Good luck with that.
The solution: Strategic voluntary dismissal to expedite an appeal.