How do I get rid of the tear in the middle of my object after using the mirror modifier? I'm sorry if this question has already been asked, but I was following a tutorial and after sculpting, I reapplied the mirror modifier but my mesh looks like this: 

Is there is any way to fix this without applying or deleting the mirror modifier.
Thank you, a blender novice
Put the mirror modifier before the multires. Keep clipping on, but make sure all the vertices at the middle are snapped over to center line.