If your Smart Object has the same pixel dimensions as your document, I think there's a way:
- Double-click the Smart Object to open its .psb file.
- Select all layers, right-click on them and choose
- Select your main document as
Destination and click
- Close the Smart Object's .psb file.
- Back in the main document, duplicates of the layers from the Smart object has appeared. Convert each individual layer to a Smart Object.
- While holding down
ALT, drag copies of the
Effects from the original Smart Object and drop them on each of the new Smart Objects.
- Turn off the original Smart Object.
- If you don't want the layers to be Smart Objects anymore, you can right-click them individually and select
Rasterize Layer Style.
This way you have copied all the liquify effects to each of the layers, but I'm afraid the result will not be as you expect. Liquifying together all the layers in one go must give another result than liquifying them individually.
If your layers had transparency when grouping them into a Smart Object, Photoshop trims off transparent pixels and makes the dimensions of the Smart Object smaller than the main document.
If that is the case it would be troublesome to get the everything aligned and I would recommend just working inside the Smart Object. You can split the screen so you can see the main document with the liquify effects while editing the contents of the Smart Object. Everytime you save the Smart Object's .psb file the main document refreshes.