Can I trade in my first generation Ipad to trade in for new Ipad Mini?

There is no trade in. The closest you can come is to sell your iPad then use the proceeds to purchase a Mini.

Your only option is to sell the iPad and buy a new one.

How to Sell Your Old iPad http://tinyurl.com/85d69lk

Other sources to sell.

eBay Instant Sell http://instantsale.ebay.com/?search=ipad

Sell and Recycle Used Electronics - Gazelle http://www.gazelle.com/

For instant gratification in selling a used iPhone or iPad, Gazelle’s Gadget Trader, an iOS app, is tough to beat. In seconds it detects the device and reveals how much it is worth in good condition. Tap the Sell This Phone to Gazelle button and the deed is done.

Sell Electronics for Cash - Next Worth http://www.nextworth.com/

Buy My Tronics http://www.buymytronics.com/

Sell Your iPad http://www.sellyourmac.com/mac-product-guides/ipad.html

Totem http://www.hellototem.com/

 Cheers, Tom 😉

Go here I think this is a good option! http://www.apple.com/recycling/gift-card/