This is kind of in my expertise. First off, this is a strap leaf and the leaves don't necessarily need to be a light shade of green. Here are a few things I would suggest you adjust.
Increase the humidity a lot more.
Switch to a balanced fertilizer 20-20-20; I use tropi-gro orchid plus but i'm not sure if its available outside of Jamaica.
Fertilize every day when the weather in your area gets warm-hot. (Wet the roots first before fertilizing as this will wash away excess salts so you won't have salt build-up)
Provide good air movement and if the weather permits get it outside & hang in a partially shaded spot or sun it outside so it can get full morning sun up until around 10:30am and then provide dappled sunlight after that and if possible full sun after 4:30pm as the setting sun is not very intense. I suggest watering early so your orchid can dry out throughout the day. As long as you water before 9am in the morning & if its really hot you can dampen it between 4-4:30pm.
Make sure it is situated in an area where it can experience a significant drop in temperature between the day & the night. Without this temp range sometimes a vanda will be reluctant to spike.
And most important; be patient. When you adjust your care and it is ready and happy it will spike.
Good Luck; i know you'll get it spiking again.