What can we do as a company when our employee break the service agreement bond?

We are an IT company, we are giving internship with job opportunity to interns who are in the final semester of their education. Because we are spending our resources to train these newcomers, we are singing a notarized bond with them before starting them as interns. We hired one intern as our employee in August 2021 with 18 months of bond agreement which cost 50 thousand. We are taking the cheque of bond amount as a security deposit at the time of signing the Bond agreement. After serving 3 months she give us a resignation mentioning that she want to do higher study for that she want time for preparation of GATE entrance test. After certain communication over email and call, with good faith & kindness we permit her to take a break of 4 months from November 2021 to February 2022 for preparation of exam and not accept her resignation. As we didn't want to make her financial loss. But after completion of 4 months, she didn't even communicate with us to resume office. When our HR called her, she replied that she is not willing to resume job. We have her cheque of Rs. 50,000/-. Can we deposit the cheque? what is the procedure to follow before depositing the cheque? I also have doubt that she will make a stop payment of that cheque, in that circumstances what should we do?