Downtime needs to be reduced while processing releases

Hi All,

We are having SQL Server 2012 which is configured in Mirroring.  Both are Standard Editions. 

These servers are configured in customer environment and we do process frequent releases on these servers. Each release includes Master data changes, Table changes, Schema Changes (some times) etc.  Usually we will take a downtime or hour or two to complete the release process. Now, our customer is asking for a ZERO Downtime setup. They are ready to invest additional hardware if needed. 

Can anyone suggest how to design an architecture to achieve ZERO Downtime with NO data loss.

Thanks,
Balu Kalepu