Can we update the DS-160 later, before the Visa Appointment or fill a new 1

Hello Folks,

Could you please let me know if we have already booked a Visa Appointment with a specific DS-160 form, and later if we change the Job or get an H1B extension approved, then can /could we update the same DS-160 (the form that was submitted earlier) at a later stage (meaning:before the appointment) OR can we upload a New DS-160 to the same Appointment Slot?

If we upload a new DS 160 form, then will the previously paid Amount be transferred to the New DS-160 form or do we have to repay it again?

The new Website is so confusing…

Please help me out