You can farm your experiences at level 6 and 11 which are office capture levels. Any other office capture level would be ok but enemies are hard to compete. I'd reccomend level 11 just because chance of combo.

Find yourself a good corner and just hold down to "q". Any other attacks are eventually move your charachter forward just by launching him. You may want to use a key pressing software just because it's gonna take some time. It took almost 5 to 6 hours for me to farm from lvl 42 to lvl 55... I used Autosofted Auto Keyboard Presser v1.9 but you may use whatever you want to.

Simply position your character to a clean corner and let it go... Images are from lvl 6 and lvl 11. You can find yourself better spots if you wish.