No promises BUT a quick search turned up this :-

https://www.graupner.com/Programming-devicefor-BRUSHLESS-CONTROL/7230/

at £28 plus post it would probably be cheaper to buy a new ESC

The specs are:
Graupner Brushless control Navy V 200
Ref: 9102
Controller suitable for model boats.
Simple synchronisation of transmission paths. Extremely precise throttle response; programming is child's play with a programming box.
Controller suitable for model boats.
Simple synchronisation of transmission paths. Extremely precise throttle response; programming is child's play with a programming box.

functions:

BEC system
Programming with programming box
Water cooling system
Adapted to meet requirements in model boats
Programming options:

Battery type: NiMH/LiPo
Cut-off voltage
Power curve
Number of motor poles in motor
Reverse mode on/off
Motor timing
Starting torque
Specification

Dimensions (LxWxH) 80x40x30 mm
Artikelbild 1 7262NavyV200001

Providing you have or can get the seperate control box to program the reverse mode to on it should be straightforward. You may have difficulty in sourcing one as Graupner are no longer trading.

Dave

The ESC is Graupner navy v 200 (No 7262)

it depends upon your ESC most of them are forwards only BUT

Esc(s) for cars and boats have reverse ( usually). Also quite a few have the ability to be programmed so you can have either on one Esc.

We need the model number and maker of your Esc before we can even begin to be more specific.