Lay the plant carefully on its side.
Pull the Pachira aquatica out of its pot by the base of its trunk. Don't force or yank on the trunk. If the tree does not come readily, run a knife along the inner edge of the pot and then try pulling again.
Brush the existing soil off the roots.
Examine the Pachira aquatica's roots. Make a few long vertical cuts through any thin, spindly roots that circle around and bind the tree's root ball. Make just enough cuts to free the root ball.
Pull the Pachira aquatica's roots out gently with your hands to loosen and spread them a bit. As you loosen, look for and prune any shriveled, blackened or mushy roots.
Plant the Pachira aquatica in its new pot using fresh soil. Make sure the tree sits at the same height in the new pot as it did in the old pot.
Water the Pachira aquatica until water drips out of the drainage holes in the bottom of the pot.