Intent i = getBaseContext().getPackageManager()
             .getLaunchIntentForPackage( getBaseContext().getPackageName() );
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);

@Override
    public void onPageStarted(WebView view, String url, Bitmap favicon) {
        view.clearCache(true);

        if(b){
            Log.d("WEBVIEW", "onFinisghed b true");
        Map<String, String> noCacheHeaders = new HashMap<String, String>(2);
        noCacheHeaders.put("Pragma", "no-cache");
        noCacheHeaders.put("Cache-Control", "no-cache");
        view.loadUrl(url, noCacheHeaders);
        b = false;
        }...

CookieManager.getInstance().removeAllCookie();

CookieManager.getInstance().removeAllCookies(null)