Small cells can offload macrocell traffic, improve indoor coverage and cell-edge user performance, and boost network capacity. However, backhaul is one of the key constraints for future small cell networks. In this paper, we investigate the refunding mechanism for small cell networks with limited-capacity backhaul, in which small cell holders (SHs) can serve guest users (GUs) with their remaining backhaul capacity. In return, SHs can receive refunding from mobile network operator (MNO) as incentives. Specifically, we formulate this problem as a Stackelberg game with MNO being a leader and SHs being followers. The MNO decides individualized refunding and interference temperature constraints to different SHs. Subsequently, each SH serves GUs in a best-effort manner while maximizing its utility function in terms of refunding and logarithmic throughput. To reach subgame perfect equilibrium, we propose a novel look-up table approach at MNO and an optimal power allocation algorithm at SHs through majorization theory.