Reading is a bit weak. If you want to get a just pass, I think your current score should be enough. No need to do prep class.
The main difference between N1 reading and N2 reading is that N1 reading tend to be more abstract (dealing with things like Japanese history, economics, biology, psychology, machine learning etc.). Also, usually there will be 1 passage that is 横書き。You can take a look at the below sample paper. This is based on 2018 Dec's paper.
https://www.jlpt.jp/samples/sample09.html
For listening, you can compare the difference below.
N2 Listening:
https://www.youtube.com/watch?v=kiRtXlmeVyY
(based on 2018)
N1 Listening:
https://www.youtube.com/watch?v=NjzTtbBK1Ls
(based on 2018)
Spend more time on grammar and reading. You might also want to go get some N1 practice papers to do to see how you fare.
After you pass N1, then it will be the start of your Japanese learning journey. This is because at N1 level, your vocabulary knowledge is only equivalent to a primary 6 Japanese kid.
I got my N1 in 2010, but I am still learning. I retook my N2 in 2018 and got a 153/180.
がんばってください! =)