Speak to your landlord about the situation. It may be that, even if the roommate has not signed a release, your landlord will allow you to commit to a lease renewal and will also execute a lease that omits your former roommate in the event that she does not appear to sign the renewed lease.
Meanwhile, perhaps you should remind your roommate that as long as she's on the lease, she's legally responsible to the landlord for rent and damages to the unit, such that if she's no longer living there it's in her best interest to be released and to never have to face the possibility of being billed (or sued) for a rent debt or damages she didn't cause.
No.

