Can the applicant apply for a utility model patent again?

If you can't apply for an invention patent after your utility model patent is authorized, even if you do, it will be rejected.

If you really want to apply for an invention patent, you can do it in the following two ways:

1, request to withdraw the utility model patent application, and then apply for an invention patent immediately for the same content.

or

2, apply for a patent for invention, and request the priority of the previously applied patent for utility model, however, the conditions of this way are; It must be within 12 months from the date of filing the previous utility model patent. Otherwise, this method will not work.