Assuming water is in the base, just put a little bit in a shallow bowl and add drops of water - preferably distilled water ... maybe 4 drops of GA to 1 drop of water. It might not sound like much, but the one drop of water is not only diluting the GA, but because the pH of the water is higher, it is decreasing the bioavailablity (making the "effective" peel % less).
Alternately, you can dampen your face with water, blot off excess (but don't dry your face), and then apply the GA right away. The water on your skin will dilute the product. HTH
Kathy