If Japanese troops retreated from Singapore

How might Japanese troops react if ordered to surrender after failing to take Singapore?

They would probably retreat north, producing a race between Japanese resupply and British efforts to pursue, interdict supplies, and establish a new defensive line in Malaya.

Troops ordered to surrender would be more likely to withdraw if their supplies had failed. British forces at Singapore would have limited means for an immediate pursuit, allowing the Japanese to fall back north toward surviving logistics. The British would try to establish a defensive line partway up the Malay Peninsula while disrupting that resupply. The outcome would depend on whether Japan could reorganize before the defenders converted survival at Singapore into a wider operational recovery.