Are we responsible for the late fees that have incurred on this loan or are we in the clear because the loan was not reaffirmed?

If you want to keep the home, you must remain current. However, if you decide to "walk away" from the home, you will be clear.

I suggest you pay the late fees to avoid being in default.

In New Jersey, the personal liability on the Note ( your personal promise to pay) was discharged. However, the Mortgage (collateralization of the Note) is still recorded against the real property. What that means is that if you ever want to sell the real estate or have a free and clear property, the debt, including escrows and late charges must be paid. If the property goes to sheriff sale the lender cannot chase you personally.

You do not have to pay the late fees, but understand that not paying may come with the repercussion of having the property foreclosed on. You may not owe on the mortgage because of the bankruptcy discharge, but the property owes the mortgage and I would expect it to weep bitter tears if it was ripped from you for being foolish enough to not pay late fees and catch up on what is past due.