The goal of the research presented in this paper is to support a user when exploring for a large amount of statistical data to make decisions and solve problems. In such an exploration task, the user tries to make beneficial discoveries by viewing data from multiple perspectives and examining them with a variety of emerging hypotheses, by repeatedly interacting with the data. During exploration, the user often reflects on his/her past explorations to consolidate his/her findings or to organize subsequent exploration strategies. Our InTREND (an Interactive Tool for Reflective Exploration through Natural Discourse) system supports such interaction by: (1) interpreting the user query represented in natural language, (2) generating an appropriate graph by considering previous interactions, and (3) presenting the history of past explorations as a two-dimensional map. This paper first describes the interaction design criteria for encouraging user exploration and reflection activities. Then weexplain the user interface of the InTREND system.