[Context and motivation] Most requirements engineering (RE) approaches involve analysts in gathering end-user needs. However, we promote the idea that future service-based applications should support end-users in expressing their needs themselves, while the system should be able to respond to these requests by combining existing services in a seamless way. [Question/problem] Research tackling this idea is limited. In this research preview paper we sketch a plan to investigate the following research questions: How can end-users be facilitated by a system to express new needs (e.g. goals, preferences)? How can the continuous analysis of end-user needs result in an appropriate solution? [Principal ideas/results] In our recent research, we have started to explore the idea of involving end-users in RE. Furthermore, we have proposed an architecture that allows performing RE at run-time. The purpose of the planned research is to combine and extend our recent work and to come up with a tool-based solution, which involves end-users in realizing self-adaptive services. Our research objectives include to continuously capture, communicate and analyze end-user needs and feedback in order to provide a tailored solution. [Contribution] In this paper we give a preview on the planned work. After reporting on our recent work we present our research idea and the research objectives in more detail.