You can port your number to Google Voice, then just set up the Google Voice app on your new phone to always use google voice to make calls, and set up your new phone number as your forwarding number on Google Voice.
Then you would keep the same number no matter what phone you ever get on any carrier.
Then just sign up for new prepaid service.
"Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery? Forbid it, Almighty God! I know not what course others may take; but as for me, give me liberty or give me death!"
-Patrick Henry, March 23, 1775