You could select your sphere, Particles > Emit from Object > Options.
Choose Surface Emitter type and adjust your rate and speed like you want.
Then, go to Window > Relationship Editors > Dynamic Relationships window.
Select your already created liquid particles and click the "emitters" option at the top. The emitter you originally had will be highlighted, while your new emitter won't be. Unhighlight the old one and select the new one. Now your liquid particles will emit from the new emitter.
Now you can delete the new particle object automatically created when you made a new surface emitter and the old emitter.
I'm not sure about assigning your already created emitter to a surface... if anyone knows how to do that, I'd be interested. But above is what I would do.