Hi Maggie,
That is a very pretty Pachira.
Sometimes when soil dries out too much it loses its ability to absorb and retain moisture (like a dried out old sponge) and the water floats on the surface for a long time before running down the sides of the rootball. Could that have happened to the Pachira? It could be the cause of wilting leaves if water isn't adequately penetrating the rootball.
The solution is to rewet the soil by removing the inner pot and soaking it in a sink of water for about half hour.
I empathize with your desire for rapid growth but repotting to larger pots doesn't make
plants grow more quickly and could actually harm them. Aside from genetics, over which you have no control, adequate light is the most important factor in a
plant's health and growth rate. A newly repotted
plant will grow new roots to fill the larger pot before
growing new foliage so it could take a long time before new growth is visible. Most houseplants prefer to be potbound. It is very easy to over water a
plant in too large a pot because the soil stays wet too long. Evenutally this leads to root rot. A general rule of thumb is that unless
plants require watering more frequently than every third day, better to leave them alone. If repotting is necessary, use a pot only one size larger.
Why don't you first try rewetting the soil to see if that makes a difference? There should be a visible improvement within a few days if that is the problem.
Please let us know how you make out. If rewetting doesn't help, we'll help you explore other avenues.
BTW, tell us more about the light the
plant receives. Is it directly in front of or to the side of a curtained or uncurtained window? What direction does the window face? Is the light obstructed by
trees, buildings, or a roof overhang?