You can increase the surface area of a block of ice by

Surface area of a solid object is a measure of the total area that is occupied by the surface of object. 

If two objects has same mass, then smaller size particles will have greater surface area. 

Thus, in order to increase the surface area of ice, one can crush it into small particles. Due to crushing, particles will break into smaller size and eventually this will result in larger surface area.  

Abbreviated as mg-25.