Originally Posted by Keihas
Can't you just start a new game? I think the arcade wins are cumulative across all your saves just like the 4000 kills achievement.
Bit of a long bump but I just got the 100 arcade wins, but it was in a single game file. At first I thought the auto update screwed with my game, but it was because I used one of my newer saves.
If you have trouble with non-respawning enemies then go to Mephistos Realm, kill four enemies then go through the portal, kill four enemies in that area and teleport back. Repeat that until all of the enemies are dead in the first area, then start on the second.
Once everything is dead then continue to Sepulcher, here there are loads of enemies to get rid of. Be sure to kill ONLY FOUR of them every time. You should be able to get the majority of your wins in this area alone. I managed about 80 because the enemy count kept glitching and they would respawn as I moved around the map.
It took a while but it is doable in a single day.