Is this your Mimosa x Orange Punch? It rather doesn't look like the photos in that diary but that's the only diary you have...
Have you checked your pH? If this is out of range, your plant will not be able to get at the calcium that you give it even if you throw a whole bottle of it into the soil! Likewise, if you've been feeding it too much nitrogen, this can also cause a lockout of calcium with the same results... Since not even the diary I can see on your page indicates any nutes that you're giving THAT plant, there's no way to tell what's going on with her. The only thing I CAN tell you is that the damage done (the yellow leaf tips) will never get better so you shouldn't be looking for that... if you've solved the problem, then all you should expect is to NOT see further damage after a few days....
Good luck