You might have to start from level 1 to get any benefit from "player.advlevel". That's what I just did, was about lvl 40 archer that would 1 hit mobs while sneaking(playing on Master obv...) and I also exploited the crafting system to the tune of $40000 gold - in other words the game was pointless to continue. Made a new game, loaded the "PISE Improved SkyRim Experience" mods, also used the command to stop all health regen in battle, also played with the level command and exited the cave to skyrim at level 51 lol....just to see how it would be, tested it on the bandits at the camp just outside WhiteRun and I couldn't even do any damage on them with my bow in sneak mode, then they 1 shotted me. Decided that was a bit too extreme, so loaded back and lowered the level increase to 26. So I am starting the game with most mobs having 25 levels on me lol. I am also playing the same type of character as before, wood elf archer. It's nice to know that I might actually NEED to exploit the trades and use my perks wisely in order to advance in the game. This game is very challenging now, as I also added most of the optional mods in that "Improved Skyrim Experience" pack, so now mages have healing spells, humanoids have health potions and use them, prices are higher at stores, sell price lower, etc etc