@Faarian
To get from 2400 to 2500 GM Sam Shankland doubled the amount of training he did for one year.
At 2000/2100 I am sure you have some type of training regime already. Compare your training to how GMs/IMs train, see whether you are lacking in some area.
I think a large part of improvement as you are going to 2000s is preparation. Preparing for tournaments, for your opponents is much more important at that level. Looking through your opponents, understanding their psyche and how they think are extremely important traits to develop.
Im still trying to break 2000 ='(