wmtsLayer.dispatchChangeEvent();  // Method 1

wmtsLayer.getSource().dispatchChangeEvent();  // 2

wmtsLayer.getSource().updateParams({"time": Date.now()});  // 3

wmtsLayer.getSource().changed();  // 4

map.updateSize();  // 5

wmtsLayer.getSource().refresh();  // 6

// 7:
var source = wmtsLayer.getSource();
source.tileCache.expireCache({});
source.tileCache.clear();
source.refresh();

// 8 (deleting the layer and making a new one):
map.removeLayer(wmtsLayer);
fetch(WMTS_URL + "&time="+ new Date().getTime()).then(function(response) {
    return response.text();
}).then(function(text) {
    var result = parser.read(text);
    var options = optionsFromCapabilities(result, {
        layer: FULL_LAYER_NAME,
        matrixSet: SRS_NAME
    });

    wmtsLayer = new TileLayer({
        opacity: 1,
        source: new WMTS((options))
    });
    map.addLayer(wmtsLayer);
});