Do I have to purchase another AppleCare for my iPad or Can I add it to my other applaecare I have now

Each purchase of AppleCare+ is for one device. So, even if you bought AppleCare+ for, say, your iPhone, if you want out for your iPad, you'll need to buy it again fro the iPad.

AppleCare - Apple

Buy an AppleCare plan for your device - Apple Support

You can't buy more than one AppleCare per product.

Glad it helped.