Purpose. Patient-tailored cervical cancer brachytherapy applicators may improve treatment outcomes over clinical applicators. There is a need for automated design and treatment planning as this is a complex, time consuming process. The ARCHITECT project has developed fully automated 3D printed personalised applicators, matching and improving conventional treatment. However, small postprocessing modifications may often be needed as it is difficult to quantify all criteria used during treatment planning. Current treatment planning systems allow physicians to adjust dwell times, but do not support modifications to automated needle configurations. This work presents an approach for real-time needle replanning in patient-tailored applicators demonstrated through a graphical user interface. Methods. Our approach to perform real-time replanning consists of a heuristic convex-decomposition step followed by quadratic optimisation. Safe flight corridors (SFCs) were generated by inflating a symmetric ellipsoid around automated trajectories and iteratively selecting tangent planes to form a convex volume. Needle trajectories were represented by Bézier curves and optimised considering the boundary volume constraints. Replanning could be done by the user by modifying the interstitial part of the needles through a graphical user interface developed in MATLAB. The algorithm was tested with a database of 20 patients, a dosimetric study was carried out with 5 of those patients and the GUI was evaluated with a usability study involving 8 participants. Results. Replanning of individual needles could be performed in <1.0 s with optimisation times of ~0.01 s followed by a feasibility check of 0.5 s. SFC generation and trajectory optimisation were tested with 99 needle channels (20 patients) showing an error rate of 17%. Replanning in a case study to demonstrate dosimetric benefits in 5 patients was feasible, however, did not lead to clear improvements in dose conformity. The interface received a usability score of 73 (min=57.5, max=92.5) from participants. Conclusions. The algorithm and interface were validated and used successfully. However, their use in a clinical setting requires improvements or exploration of alternative approaches to increase robustness.