There is a way to respec, up to a point.
You have the option to respec your 3 most recently spent skill points. This means that you can invest a little into a combo of skills that you want to try, and if you do not like it you can claim up to three points back.
To get a respec visit the NPC in Estherian Enclave, the first town you will find, who will perform skill respecs for you at a small gold price.
You cannot respec your Strength, Dexterity, Focus, and Vitality attributes.
However, as pointed out in @ShameFulmer's answer, if you don't like the built-in system, you can modify your save file instead. The easiest way is to replace your shared stash save file with one that is full of respec potions. There is such a file available on the forums as Shared Stash Respec Potions.
This does not mark you as a cheater.
To summarize the instructions on the forum, being careful to not delete everything currently in your shared stash (it wouldn't hurt to move everything valuable out of there):
Ensure that the game is closed and that Steam Cloud saves are disabled.
Backup your shared stash save located in
C:\Users\< username >\Documents\My Games\Runic Games\Torchlight 2\save\RandomNumber (replace < username > with your username). It should be called
sharedstash.bin. You can either move it somewhere else or change its name.
Download the file from the forums and save it to the same location. This will replace your shared stash with respec potions.
Open up the game, load the character you want to respec in a single-player game and take as many potions from your shared stash into your character inventory as you want.
Close the game and restore the downloaded
sharedstash.bin with the file that you backed up.
Re-enable Steam Cloud saves, and enjoy the game! You will still have your old shared stash and your character should be carrying all of the potions that you took out. You are free to put them back into your shared stash and use them with other characters as well. Using these potions will not mark your character as a cheater, like some other methods do.