LM3S6911: LM3S6911 upgrade

Part Number: LM3S6911

Tool/software:

We have an old design that uses a LM3S6911-IQC50-A2 in a 100-LQFP package. We would like to update it to a new processor with the same software and only hardware changes. Can that be done? 

I would like a recommendation on what part to use for the upgrade and what would be tasks would be required to complete the upgrade.

Thanks

Dennis