We present a conformal inference method for constructing lower prediction bounds for survival times from right-censored data, extending recent approaches designed for type-I censoring. This method imputes unobserved censoring times using a suitable model, and then analyzes the imputed data using weighted conformal inference. This approach is theoretically supported by an asymptotic double robustness property. Empirical studies on simulated and real data sets demonstrate that our method is more robust than existing approaches in challenging settings where the survival model may be inaccurate, while achieving comparable performance in easier scenarios.