Investors & landlords

I did follow the depreciation of the new refi costs at 30 years but how do I take care of the old depreciation of the refi costs?  Do I just retire it and add the remainder to the new refi costs? Or do I just start a new depreciation entry for the old refi cost at 30 years? Also, would i depreciate for the remaining amount or the full amount of the old refi cost.  Where do I find the remaining amount? Thank you.