You'd need to find a schematic of the pedal, or someone who is good with electronics (if you yourself are not). Then you would need to see if there is a filtering capacitor at the input or output stage, which you would then replace with a more bass friendly value. Additionally, or instead (depending on the circuit), you may also need to change the capacitor value(s) of the tone control (if any) of the pedal to allow more bass to pass through. You could also contact any number of small effects builders, such as
[SFX] who is a member here, about modding your pedal for you.
Another way that you could make the effect more bass-friendly is to put it into a blend loop. It essentially mixes your effected signal with the original clean signal coming from your bass, as if you had two bass amp setups with one clean and one effected (okay, it doesn't sound
exactly the same... but you get the idea!) There are many pedals that achieve this on the market, including the Xotic X-Blender, Wounded Paw Blender, and the BOSS LS-2 to name a few. Just do a search on here or elsewhere to learn more about them.
