This feature is built into the game now! You can right-click a skill to refund it.
Allows you to refund individual skills without respecing the entire tree!
To refund a skill, simply select it once it's aced or you have no more points to spend. You may also refund skills by selecting "no" when unlocking the aced version, which will prompt a refund.
You will be refunded half of the cash invested in each skill refunded, just like a full respec. Unlocked tiers will be validated and skills you no longer have enough points to unlock will also be refunded.
Now you can tweak your builds without completely scrapping them!