Upgrading from SCSP to DCS:AS

I posted this is CSP as well but it looks like that's not viewed as much, so I am hoping someone here can answer this.

We currently have Symantec CSP and I was looking at upgrading to DCS:AS as it is CSP rebranded. If we have maintenance on CSP can we get a license for DCS:AS or do we need to rebuy the whole thing? If so any idea if there is a discount or anything?

Thank you!