I'm considering doing JuVaShape on my stomach. Is it safe for breastfeeding moms and is it safe on reproductive organs?

JuVaShape is a good option for skin tightening around the midsection. Although it will depend on how much laxity you have. In some cases, if the laxity is excessive it's better to have surgery done to resolve the issue.
Best to consult a doctor who treats skin laxity issues.
I'm not aware of any issues or contraindications  using radio frequency during breast feeding or its effect on reproductive organs.

Juva Shape is good for tightening loose skin in some cases.  Depending on the laxity you have, you may or may not be a candidate.  Your best bet is to consult with a physician that has many different approaches to offer so that you can obtain your goal results.  Good luck.