If after masturbation you took forty steps or relieved yourself or slept for a lengthy duration and then took Ghusl, then renewing your Ghusl will not be necessary if liquid emerges (after Ghusl was completed.) You are simply required to wash off the liquid (from the body and clothing) and perform Wudhu if you intend performing Salaah.

However, if liquid (in the form of remaining semen) emerges without carrying out any of the above, then Ghusl should be repeated. This is the view of Imaam Abu Hanifa and Imaam Yusuf Rahumahumullah which is applicable under normal circumstances, and is in fact, the precautious view.