In recent years, a substantial shift from the web of documents to the paradigm of web of data is witnessed. This is seen from the proliferation of massive semantic repositories such as Linked Open Data. Recommending and adapting resources over these repositories however, still represents a research challenge in the sense of relevant data aggregation, link maintenance, provenance and inference. In this paper, we introduce a model of adaptation based on user activities for performing concept adaptation on large repositories built upon extended generic ontology model for Adaptive Web-Based Systems. The architecture of the model is consisted of user data extraction, user knowledgebase, ontology retrieval and application and a semantic reasoner. All these modules are envisioned to perform specific tasks in order to deliver efficient and relevant resources to the users based on their browsing preferences. Specific challenges in relation to the proposed model are also discussed.