Is there any way to stop the SOL period from starting again?

Which state does your friend belong to?

In your case, the SOL will not start in most of the states. The creditor can only keep his fingers crossed and wish your friends' honesty continues. However, if your friend signs any written agreement for making the payments, this will reinstate the contract and start a new SOL period. Legally it is called "reaffirming the debt."

She won't get back the amount she paid
The SOL period has started again since your friend has already made a payment
There is no way to stop it now.

Often the collection agencies pursue to start making payment and then to negotiate a settlement. But, never agree to that. Always check the SOL period before you start negotiating and making payment.