Interact with your class Skill Station and select the skill you wish to retrain from the menu. Also, aim to place stations together in an easy to find location. Otherwise, your teammates would need to leave your realm in order to respec.

But, if you plan on engaging in frequent multiplayer games, it would be a good idea to make Skill Stations for every class. In single-player you will only need one station. First, you will need to build a Skill Station, specific to each class: To actually repec, you need to return to your Fort. Using Respectacles at Your Fort in Torchlight 3 If your character is strong enough, battling against harder enemies is your best option. Additionally, some armor pieces will also give enhanced Potion Luck. Painful difficulty will further boost this bonus to +30% Potion Luck, and Ridiculous to +40% Potion Luck. Playing at Normal or Hard difficulty gives a +20% Potion Luck over Practice mode. These items are considered consumable potions, so they will be easier to find by raising Potion Luck. Additionally, you can respawn bosses by logging out and back in to reset the game's instance. This means you can start farming them even after the first boss encounter. Respectacles can drop from any boss monster but will have a higher chance of being loot from story bosses and chests. Instead, further repec points can be earned by collecting Respectacle consumable items. This doesn’t leave a lot of points to retrain, as characters currently gain nearly 60 skill points. Characters earn their first point at level 5, and then another free point every 10 more levels (15, 25, 35). Retraining a character is used via “Respectacle” points.

Torchlight 2 full respec