Replace some of your coconut oil with palm kernel oil, they create the same big cleansing bubbles. Using too much coconut oil with make your skin dry and sometimes itch. Higher than 15% is not recomended. You can also use regular palm oil to harden up your soap, but it wont create big cleansing bubbles like palm kernel and coconut, regular palm will create a creamier lather. Also butter creates a creamy hard bar. Cocoa, shea or mango butters. If worse comes to worse, you could just resort to crisco or lard, they act simular to regular palm oil.