I normally get amazingly fast results from Sparkolloid, like next day clear... but I only use it in wines that have been sitting for months and still have not cleared....BUT, they have no CO2, as pumpkinman said above that CO2 can keep things suspended and floating around making harder to clear.
If it is pretty new, you might just walk away and let it sit...time and gravity are your allies here. FWIW...EVERY batch of wine I have had a problem with was created by me trying to rush things and each problem was solved by adding more time to the process. Sometimes you get there faster when you quit peddling and just coast downhill!