First, welcome to the forum -
Second, I'm assuming that your question is if you leave your iPad plugged in most of the time (i.e. w/o the battery discharging), will the battery last longer?
Well, the short answer is NO - the Lithium-ion battery technology is pretty mature at this point; the battery is meant to be discharged periodically (not completely - maybe to 20% remaining charge) and should last for many charging cycles, i.e. you likely will replace your iPad before the battery gives out!
There will be be many opinions given w/ some likely conflicting - take a look HERE
for some more information and checkout the advice on the iPad Guide book.