Of course you should write that stuff!!! Plus if you have any advances in your volunteer work or interests/sports, you can add that too. But just as importantly as giving the "list" of your improvements is to CONTEXTUALIZE it! Meaning, the school wants to see more than a bunch of random improvements, they want to see you stubbornly persevere towards your goals, and they want proof of that progress. And actually it sounds like you have a lot of good new info to give them, so make sure it is all there. At the same time, you should be carefully analyzing your last year's applications to identify your weaknesses, and to make good on them.
All the best,
If you like the post, give it a KUDOS!