FCTM "If an engine fails during GA, perform normal GA and Missed Approach procedures. Verify max GA thrust is set. Maintain flaps 15, Vref 30 or 40 +wind correction speed and limit bank angle to 15 deg until initial maneuvring is complete and a safe altitude reached. Accelerate to flap retraction speed by repositioning the command speed to the maneuvring speed for the desired flap setting and adjusting pitch. Retract flaps on the normal flap/speed schedule".
The operative phrase is "maintain flap 15" and this assumes you have just set Flap 15 as part of the all engines GA procedure. Nothing about going to flap 1.