With constant temperature and humidity changes, wood WILL inevitably shrink and contract. There is nothing you can do about that. I concur; get new doors made to match your existing cabinets. It will not be a huge expense, and you'll be much happier with new doors than with trying to repair the cracked ones.
2012 Rockwood 8293RKSS
2006 Dodge Ram 2500 5.9L Cummins Turbodiesel 4x4; 2012 Ford Escape 4x4. 3 very pampered cats.
Days camped: 2011: 61; 2012: 66 Days; 2013: 69;2014: 68 2015: 90 Days camped 2016: 34