Hey charlisymone! What a lucky daughter you have! I want to make sure I'm addressing both parts of your question - if you're asking about your regular bill balance, your account will need to be current to upgrade (so as long as nothing's late, you're good to go!). Regarding JUMP! eligibility, if you have the original JUMP!, you'll be able to trade in your daughter's current phone as long as she hasn't already done so twice in the last rolling calendar year. If you have the more modern version of JUMP!, then you can trade in her current phone as long as 50% of the overall MSRP is paid off. If you have JUMP! On Demand, then you'll be able to trade it in as long as she hasn't JUMP!ed three times in the last calendar year. Phew! That's a lot of different JUMP! details.
To best prep you for your experience in store, I also want to let you know that you may have taxes and/or a down-payment due up front depending on the type of financing program you're participating in. The only other possible cost you could encounter is an insurance deductible if her iPhone 6S has any physical or liquid damage - but hopefully that's not the case. Please let me know if you have any additional questions, I'd love to help you make your daughter's Christmas morning as awesome as possible!