Robotic navigation systems for radio frequency catheter ablation (RFCA) have been used effectively in clinical practice. Compared to manual navigation, such systems facilitate the operation and reduce radiation exposure for both the patient and the operator. Furthermore, they allow for higher contact forces resulting into more effective ablation lesions. However, if excessive contact force is applied it may lead to higher risk of cardiac perforation. To ensure high effectiveness and low complication risk in next-gen robotic navigation systems, tissue heat distribution should be taken into account. In this work, a meshless computational model for lesion prediction during robotic navigation assisted ablation is proposed. The model accounts for non-zero initial conditions and time dependent boundary conditions to simulate multi-site ablation. The meshless Fragile Points Method (FPM) is employed for the numerical solution of the model to ensure its suitability for clinical application, since FPM does not require the definition of a mesh. Simulations with two ablation sites and different catheter angles during ablation are performed for a 3D block of ventricular tissue. The proposed model has the capacity to predict lesion formation effectively by taking into account the heat accumulation of previously ablated sites of a multi-site ablation. Predicted lesions by the proposed multi-site ablation model are compared with lesions obtained from conventional single-site ablation simulation. It is demonstrated that if multi-site ablation is not considered, the lesion characteristics can be underestimated by up to 24.4%. Simulating the multi-site ablation conditions, transmural lesions may be obtained without excessive contact force. As a result, the cardiac perforation risk of the robotic navigation system may be reduced.