بسم الله الرحمن الرحيم
(Fatwa: 101/96/M=2/1438)
If wudhu breaks during tawaf then it is necessary to stop it. If wudhu broke after completing four rounds of tawaf then after making wudhu one is free either to complete the remaining rounds or start the tawaf afresh. But if wudhu broke before completing the four rounds then it is better to perform the tawaf again. However, it is also lawful if one completes the remaining rounds of tawaf.
أو تجديد وضوء ثم عاد بنى لو كان ذلك بعد إثيان أكثره ولو استأنف لا شيئ عليه الخ ويستحب الاستيناف في الطواف إذا كان قبل إتيان أكثره (غنية الناسك 127)
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband