Rental use change from 50% to 100% business

I currently rent one unit of a two family home, 57.5% of the home, and will now rent both units beginning in November, 100% of the home. Excluding the land I had a gross depreciable basis of 111K, which led to a depreciable basis of 63K related to the 57.5% rental portion. I've claimed 5K in depreciation so will need to depreciate based on the 111K basis less the accumulated 5K. I know how to do the math for the depreciation and how to determine what costs to deduct, but I'm not sure if I need to file a new 4562 form for 42.5% now used for rental and depreciate it for 27.5 years, fill out form 3115 for a change in accounting method, or treat this is as a like-kind exchange? Any help on the tax implications for this change would be greatly appreciated.