Van Persie struck twice for the Gunners in their 3-0 derby victory over Tottenham on Saturday.
"In the last four or five weeks I've felt much better," he told the Official Matchday Programme.
"I've had to get used to the new role because I previously played as a second striker and now I'm operating as a main striker, so I needed to find my way in.
"To my mind, earlier in the season I lost too much energy working defensively and needed to find the right balance. It's really important for the team that I have enough energy to score goals and make assists, as well as helping out in other ways.
"I feel that in the last few weeks I've found that mix, of having the energy to do my offensive work and contribute defensively.
"It was hard in the first few weeks to really find my way - the second striker and striker are very close to each other on the pitch but at the same time there's such a difference, a massive difference, between the two roles.
" I like it because it's a new challenge for me and if you look at the results and the personal stats of almost every player, everyone has improved with the new system."