How do I increase mic volume in new iPad

Theres no way to do that, you can only speak closer to the mic or use the headphones that came with the iPad which have a pretty good mic.

You mean for how loud the recording is for the mic?

Yeah hope fully they update it, but always leave feedback at apple.com/feedback

There is no universal volume control in iOS 5 for the built in mic.

There are some external mics that can help.