How to fix modeling geometry/topology error after applying all modifiers? So I have been working on modeling a simple character, and used mirror modifier to mirror my object, but due to some problems happened while modeling, When I applied my modifiers, the part had the problem looks as if my character had a bad stomach surgery

The whole body was very regular and looking very good, but that part looked like really bad thing happend, so my question is how to re-regularize that part again? I don't care that shape of the stomach might differ, I could remodel it or sculpt it, but my goal is to regain those regular squares modeling that part again. I thought of removing all faces that are deformed and form a new big face making loop cuts, but things got very very missy.
Can anyone suggest how to solve such a problem?
I have added my blend file here, in case you would like to inspect the model much more
Enter edit mode, select the whole mesh, in the menu choose &quot;mesh&quot; -&gt; &quot;symmetrize&quot;
Then select the correct &quot;Direction&quot; in the Redo panel (the pop-up panel with the settings for the tool)
Make sure your objects origin is in the centre of the object as this is where the symmetrize-ing will be based.
Blender docs: symmetrize