Something like this?
A really great and convenient gadget!
www.amazon.in
The advantage with gadgets like this is they can auto regenerate the silica by heating it after it saturates. The other sachets are disposable and you have to keep buying them.
I was looking into this some time back, people were DIYing by getting the desiccant putting it in bags they sewed and then after regenerating them in the oven for some time. They would change colour.
That is the general idea. A humidifier works so as long as the cupboard remains shut.
In addition, it would help to have a humidity meter to monitor levels.
amiciSense Digital Touch Screen Weather Station, Blue Color Thermometer Hygrometer For Indoor Use, 2xAAA Battery Include : Amazon.in: Garden & Outdoors
www.amazon.in
The downside with cheaper meters like this is they can't be calibrated if that matters so some error of 5%+ will be there.
Won't matter in your case as you will be looking to bring the humidity down by tens of per cents.