There are enough monsters to get you to level 511 (maximum in the game). If you have the patience and keep training then portalling back to the next to last map which respawns every 4 days you can make 10 levels each trip by killing all the monsters on that map. There are no more XP bonuses after that so you are free to go all the way if you like. I got tired of it after level 311 (my highest so far), so I
quit at that point and finished the game.
NOTE: I still don't think the resetting thing has ever happened to me because the first time I train, I usually train to level 260 or so. However, I will be on the lookout for it this time around.
Could be that Grey's patch fixed that as well although I see no mention of it in his readme file.
