Refresh data on the page which have been modified in collection

Pretty sure you should be doing the refresh before trying to query and update the repeater from the cms with your filters.

But saying that I cannot see why you are refreshing the dataset and then querying the cms.

I would expect you to then use the refreshed dataset.
This should save you Having to re filter and query the cms again.

wixWindowFrontend.openLightbox('Ajout Suppléments')
    .then(async () => {
        let numResaValue = $w('#NumResa').value;

        // == Refresh datasets  to latest CMS data
        await $w('#SupplementsResa').refresh();
        await $w('#ResaEnCours').refresh();

        //  == wait for dataset to be ready
        await $w('#SupplementsResa').onReadyAsync();
        await $w('#ResaEnCours').onReadyAsync();

        // Now use new data
        $w("#supplementsRepeater").data = $w("#SupplementsResa").getCurrentItems();
        
        $w("#resaRepeater").data = $w("#ResaEnCours").getCurrentItems();
      
 });

Not tested…