Im practicing this song again after 3 months of not playing it and i need some Advice for the allegro part...becuz the double tounging is tricky and i cant get it clearly out should i be saying tu ka tu ka or something els?

I use da ga da ga because I feell the tuku does not sound as natural and and flowing for me.

It doesn't really matter what you "say" as long as you get the results you want. Those syllables are just to show you where your tongue should be placed for each stroke, and everyone is comfortable with a slightly different variation. You can use Tuh-Kuh, Duh-Guh, Tee-Kee, Doo-Goo, or any number of other syllabic devices. What really matters is that you get two distinct strokes with the tongue, and that you're able to control them well. Experiment until you figure out exactly what placement works for you. And to ensure evenness in the sound as you double tongue, reverse whatever syllables you use (tuh-kuh would become kuh-tuh). This is important as oftentimes the first syllable will be emphasized slightly more.

whatever you use, it should be smooth, but you don't learn to double tongue by playing a difficuly piece, you spend 30 min. a day playing scales first slurred, then double tongue, gradually increasing your speed and accuracy..

ohh okay