X visa are issued for students wanting to study in China for more than 6 months. If one holds a different visa, generally speaking, one would need to leave China and reapply for an X visa. You may consider obtaining a visa while staying in Hong Kong, which is the most convenient place to apply for a new visa or to extend the current visa if you are living in China now. You can also check the local PSB and see if they can issue a new visa (and resident permit) without the applicant having to leave the country.