Unfortunately, appraisals are mostly based on what homes of similar size and functionality in your immediate area have sold for in the last 6 months. Although improvements made may add to your enjoyment of the home, unless they are uncommon to the area they will probably not add much if any to the appraised value. An addition to the home, or maybe a large deck or patio built might add a little. Updating the kitchen or bath, or replacing the furnace or roof would not.
My recomendation is to be present when the appraiser comes through. You can indicate the improvements made to the appraiser and maybe it will help a little. But do not expect the improvements you've made to add value dollar for dollar or even close. Lenders are being very conservative these days and they would rather turn down the business then take on the risk if there is even a speck of doubt as to the value