Once you install the Immortal Throne expansion, you can import characters from the original game to the expansion, with the option to rename them. You can use this to start new characters at a higher level.

To do this, start a new character on the original (non-expansion) Titan Quest. Raise that character a few levels without selecting a mastery or allocating stat points. Now, you can import and rename that character in the expansion as many times as you like, effectively allowing you to start new characters at a higher level, with all points unallocated!