So what this is doing is it looks in the translation file for the area actions for the key refreshNode (because ActionRefresh.Instance.Alias returns refreshNode):

<area alias="actions">
    <key alias="refreshNode">Reload</key>
</area>

This can be done using the testService as well:

var textService = ApplicationContext.Current.Services.TextService;
var refreshNodeText = textService.Localize("actions/refreshNode");
menu.Items.Add<RefreshNode, ActionRefresh>(refreshNodeText, true);

You may need to add a using: using Umbraco.Core.Services;

Of course it's better to keep using the constant value:

var refreshNodeText = textService.Localize(string.Format("actions/{0}", ActionRefresh.Instance.Alias));

Hope that helps!