One of the main challenges of co-simulating hardware-in-the-loop systems in realtime over the Internet is the fidelity of the simulation. The stochastic delay of the Internet may significantly distort the dynamics of the network-integrated system. This paper presents the development of an iterative learning control based approach to improve fidelity in such network-integrated systems. Towards this end, a new metric for characterizing fidelity is proposed first, which, unlike some existing metrics, does not require knowledge about the reference dynamics (i.e., dynamics that would be observed, if the system was physically connected). #ext, using this metric, the problem of improving fidelity is formulated as an iterative learning control problem. Finally, the proposed approach is utilized in a case study, which shows that the proposed approach can significantly improve the fidelity in Internetdistributed hardware-in-the-loop simulation.