Is there a chance of a child outgrowing jra?

Yes. Jra is divided into different types depending on the number of joints involved and whether the child has recurrent fever and a rash. Some types such as pauciarticular (fewer than five joints involved) jra resolve in over 50 percent of cases. The prognosis in all types is much improved given modern medicines that can help prevent long term problems in this disease.
No. There is no way to "outgrow" jra / jia. It can only be put into remission for periods of time from weeks to years, depending on what type of juvenile arthritis it is and how many joints were involved at the time of diagnosis. Kids with more active joints at diagnosis are more likely to flare more often when off meds. Until a cure is found, we work for remission with minimal flares of disease.