Parsley2 has a data-parsley-group feature that you could leverage in your multiple steps form case.
If you add a data-parsley-group="step1" on all your step1 inputs, and then do when you click on next (you'll need to bind this button to 'click' event), simply do $('#yourform').parsley().validate('step1') and check if true or false to go on next step.
I'll try to add this kind of example in the documentation soon.
EDIT: Tadaa http://parsleyjs.org/doc/examples/multisteps.html
Best