It sounds like you want to keep it. If you're going to keep it, you may want to see if you can pay back part of the loan w/ the $6K in cash value. It's usually called a partial cash surrender. You may not be able to take the full amount w/o closing the policy. If you have to pay $4K + $840/yr for 34 years, you'd have spent ~$29K for the ~$100K.
Usually permanent insurance isn't an ideal investment, but since you're already 20 years into it before you start paying, it's not a bad deal, really. I would figure out if there's a way you can stop your mother from taking another loan w/o you knowing (as she already has). If you can't be sure she won't do more damage to the policy, it may be best to let it go.
One aspect of this you didn't ask about, but one that I would keep in mind is this: The cash value goes away (back to the insurance company) upon death. If you're looking at the death benefit as the gain on your investment, there is absolutely no reason not to use the cash value before your mother passes, if you don't, it's gone. This is usually a missed part of the sale of life insurance. People see building cash value plus death benefit on paper, but in reality, if the cash value isn't cashed the policy is only good for the death benefit.