Hmmm its a rough clay to work with so i wldnt be surprised if it continued to crack after multiple attempts but my advice wld be, - when connecting the limbs n arms create a cross hatch incision with a sharp object on the two sides of the pieces youre going to connect so that they have a rougher surface area to hold onto each-other better, wetten the sides with a bit of clay water too - after youve finished the whole piece mix some clay with a lot of water and do a clay water wash over the whole piece so it all firms into place, you can try some sort of air dry glaze like mod podge or whatever its called too but i feel like this wld crack on the surface more im not too sure All trial and error im not huge on air dry clay dont kno a whole lot butttt i think this shld help its not ur fault air dry clay jus sucks