Can I use the 'Create sub products option' more than once?

Yes you can create sub-products for each product you have on your form. First you need to setup the quantity property. You can see here more details:

http://www.jotform.com/help/264-Create-Sub-Products-Based-on-a-Product-Option 

You can test the demo form: 

http://form.jotformpro.com/form/50405726253955? 

Let us know if we can assist you further.