Now I did not come here to clear karma, learn anything in particular or achieve some unobtainable goal; I came here through the sheer appreciation for this place and life... and I highly doubt that anyone does it otherwise (but then what do I know)... other than it would not make sense... at least it makes better sense that people from a place of suffering comes up with ideas about why they suffer in this life, that differs greatly from those who are in alignment with the appreciation of source
So my answer is you don't HAVE to come back here, and if you do then it will be because you desire to... not because you have to
