Reuse rig for another character

Is there a way for me to reuse a rig to create another character without creating a whole new rig?

Only if your other character is going to be exactly the same build.
The proportions between the drawing pivots would have to be the same, the naming of the elements/drawings, the order of the layers, etc.
You would save a copy of your character to use as a template for your new characters and basically just redraw the character, element by element.
That way you could reuse animation templates from one character to the next.

However reusing rigs/animation from one character to the next is definately NOT one of Harmony’s strong points, as it doesn’t have a true bone system.

Toon Boom have put up a simple blank rig template that you could use or build on.

https://www.toonboom.com/resources/templates/blank-rigging-node-system-template

I reuse a character rig I’ve created myself. Like MartinT said, you just have to delete and redraw each element, and then adjust the pivots and deformers and then rename the elements. I have all the layers named in my template rig like Arm_01, Arm_02 etc so when I reuse the rig to create a a character I only have to add their name at the start eg. For a character called Karate Rabbit my naming convention would be KR_Arm_01, KR_Arm_02. My pegs have a ‘P’ added eg. KR_Arm_01-P.

I know it sounds like a lot of work but I find that setting up a rig takes way longer. Also, doing it this way you have a consistent rigging system with all your characters.

Also don’t forget to create a new Element palette for your new character. If you use the same linked palette and put the newly created character and the old character in the same scene, all of the color from the new character will revert to the old character’s colors. So make sure you create a new Element palette within the new scene and change the colors!