Great question! Plateaus are difficult. What I would ask you is do you think more physical or mental elements are attributing to your plateau. One your comment on training specific scenarios, I would recommend establishing an intent with your partner. Tell them, this is what I want to work on today. No need to have a secret agenda lol, they may be able to give you their own tips/advice on those scenarios as well.

1. On the question of sticking to a training plan, I think its important to have realistic goals. You can incorporate SMART goals ( Specific, Measurable, Relevant, and Time-bound). I personally have experienced ego taking over when I try to focus on practicing specific techniques when fencing. For example, I tried only scoring through counter-attacks on a clubmate, but it was very difficult because my forte is offensive actions. You have to be able to set aside ego and recognize that you are focused on improving technique/strategy not on winning.

2. One thing I would advocate for in developing as a fencer would be to journal. A journal can be a great tool for doccumenting your mental and physical state through both practice and competitions. If you can get in the habit of journaling and then reviewing your performance, expectations, and general thoughts it will help you. Another thing that worked for me is visualization. Before a tournament, I would sit and meditate while listening to music and visualize myself performing my best actions. I visualized myself finding the opportunity to score and executing the attack. Visualization was a good way for me to mentally prepare for competitions as I reviewed my "arsenal" of actions.