"Degrees" has several meanings, such as "six degrees" of separation, or "180 degrees Centigrade." While "180 degrees" is often used to describe a reverse in direction (make a one-eighty) it doesn't fit in your example. You could say, "all of a sudden she makes a complete turn-around," or casually, "makes a one-eighty." You may say that a person's condition is improving by degrees, that is, incrementally. But your sentence seems to try to measure her improvement by a specific number of degrees. Why not ten degrees? Degrees of what? Certainly not degrees of rotation.
If you can say she's 180 degrees better, then you should be able to say she's 200 degrees better. That would be "even better!" But as you must know, only 180 degrees represents a complete reversal, for better or for worse.
Since we're talking about degrees as on a compass, 180's work best when talking about direction. Her condition was growing steadily worse. Suddenly she made a 180 degree turn-around. You can't say "a 180 degree improvement."
You can't say, "Her condition was terrible. Suddenly it changed (by) 180 degrees. A terrible condition is static. Do you mean it got better or even worse?
But you could say "Her prospects were terrible. Suddenly they changed (by)180 degrees." "Prospects" indicate a direction. They changed from bad to good. This may seem complicated. And people may misuse the concept.
You can describe two static positions as 180 degrees apart, as in the positions of two political candidates. If they're on the circumference of a circle, that's as far apart as they can possibly get.