At present, the cloud marketplace becomes more and more widely used for delivering cloud applications to consumers. The diversity of IaaS and PaaS services from many cloud providers gives customers many choices that benefit them the most. If a customer is not satisfied with his existing cloud resource service (IaaS or PaaS), he is going to stop using the service in use and consider other cloud service providers. And he also wants his cloud software bought on the market to be hosted on new cloud platforms. However, changing cloud resource services for multi-cloud application is not trivial. In this paper, we propose an approach that uses a Composable Application Model (CAM) to construct the topology of a multi-cloud application in a Blueprint. Thereby, all the changes of cloud platform services are reflected to the Blueprint. In this way, the cloud application is managed. Thus, cloud application operation is guaranteed after one or several of its software components are re-deployed on new cloud platform services and re-established application interconnections so that the operation of the cloud application is as an initial state. For updating the Blueprint, we built a bidirectional transformation system where the core is a bidirectional transformation program. We show how the Blueprint which is described by TOSCA-based specification is automatically correctly auto-updated.