-Track your stats so you know when you are just about to level up. Use the town portal door to return to town then go back to where you left off. If you do not like the random skills assigned when you level up, kill yourself. You will restart at the portal door again. Repeat the process until the upgrade skills offered to you upon leveling up are acceptable.
-When you level up and you do not like the skills available, press to shut down the game. When the game is resumed, the level up screen will reappear, but with new random skill choices.