If you use a lot of data, there's a 30GB/month plan for $160 (plus, I think, $15/line). You could also talk to them and see if they'll give you the upgrade price on the phone without changing your current contract. Sometimes they will, sometimes they won't. If the store won't, call 611, get a human and ask for Retentions. They can, most of the time, renew you on your current plan with the subsidized price for the upgrade. (It's that department's sole job to keep you as a customer, so if you don't ask for something ridiculous, they'll usually work something out with you. Something like, "well, if I go to Sprint ..." usually does it, if they won't discuss it. So does speaking with a department manager. But a reasonable request, not something they can't do, like a free Note 4. Keeping your current plan with an upgrade is reasonable.)
And never get angry or even pushy. You're asking for a favor, so be polite and calm.