If you didn't apply for a double application on the same day, but applied for a utility model, there are two ways to apply for an invention now:
1. The priority of this application in the past and now is a double application filed on the same day. However, in this case, judging from the current review, 100% cannot guarantee that the re-applied utility model can be authorized. And you may not be able to guarantee the invention authorization, and there is a situation where the bamboo basket draws water with a sieve.
2. The utility model shall go through the registration formalities as usual, and then submit the pct application, and enter China to apply for invention through the PCT. Disadvantages: the cost is higher and the procedures are more complicated, but it can enter the markets of the United States, Europe and Japan and be protected.
If you think there are problems in the writing of the current application, especially the stability and protection scope of the claims after the application, then you can completely reapply and submit two applications on the same day. Which strategy to adopt depends on your focus.