Is it possible to reset stat points in Torchlight 2?

There's no in-game way to reset your stat points, so your best bet is via a mod. My suggestion would be to use the Rapid Respec Mod. I've used it before and it's very handy. This will allow you to respec your characters stats and skills without having your character marked as a cheater. It comes with a Windows installer, so it's really easy to set up.

If you do use the mod I'd suggest turning off Steam Cloud Saving for Torchlight 2:

Turning off Steam Cloud Save is strongly recommended. Steam Cloud Save does not always respect the timestamps on files. This causes it to sometimes overwrite a save file that you have just edited with Torchlight 2 Rapid Respec with an older version of the file from the cloud.