I did a little tweak and the numbers anyhow, look a bit better for lather. I put in:
Olive oil 21 ounces
Palm oil 16 ounces
Coconut 14 ounces
Castor 5 ounces
A bit of castor will do a lot for lather as long as you don't add too high a percentage. Many people feel that 5% castor gives better bubbles than 8 or 10% even.
Other things that can increase lather are adding milks as part of your liquid (cream, goat milk, coconut milk), adding sugar (dissolved in water) at 1 tbs per pound of oils, adding honey (I'm not sure of the quantity), using beer as part or all of your liquids, adding sodium citrate at 3%, egg yolk.
Keeping your superfat at about 5% may help as well, although your recipe has a high percentage of coconut, which some feel is drying and requires a little higher superfat to balance. You could try decreasing the coconut to about 20% and increasing the palm a bit to keep the lather factor up.
Do you have any other oils/butters that you use or would consider using? I'm waiting out a cure time to see if this is true myself, but the trifecta of coconut/palm kernel oil/castor is supposed to guarantee bubbles.