If this were a non-SAP environment the folks in this forum could give you suggestions on how to perform a switch for MSA and WarmStandby configurations. And while the advice/suggestions would likely work in a SAP environment (at least technically speaking) I'm not sure how this would affect a) the SAP application management infrastructure or b) your licensing with SAP.
Since you're running SAP on ASE and using the various SAP 'tools' (eg, sap_status is a SAP-centric piece of code) to setup your replication environment, I'd recommend you visit SAP LT Replication Server (that group deals with SAP applications using Sybase's repserver) to see if the folks over there can give you more details on what options may be of use in your situation.