Is It Possible to Start Invisalign Again After Quitting with No Additonal Cost?

If you change providers to start over, I would think it difficult to find someone to do it at no charge.  Odds are that if treatment starts over with the SAME provider, there would be SOME kind of fee.  If much time has passed, then the teeth are not likely where they were previously, and the aligners likely won't work.

I would suggest NOT starting over unless you are sure you can commit to complete the treatment.

It must be with the same dentist who started the case. You may be able to start where you ended but sometimes going back to aligner #1 or 2 is needed. Going to a new dentist requires a whole new fee MOST of the time...Dr Thomas

It is most likely that starting up invisalign after quitting will have an additional fee.  Depending on how long you have quit will influence the cost. Invisalign cases are only good for a certain period of time (about 2 and 1/2 year after start date but varies) and then they expire and require an entirely new case submittal to start again.  If it has been less than that time period and your case is still active, then it is possible the fee will be less.