Kildare Town may be best bet,.
Option 1 - Dunne & Crezenci in the Kildare Outlets (some cheap outlet shopping while you're there?)
Option 2 - Silken Thomas Cafe Bar in Kildare town. Comprehensive menu, decent portions, well priced. Served all day. Very comfortable.
Option 3 - Cunninghams Bar - good bar food from 5.30pm
Option 4 - Colleseus Italian Restaurant with plenty of lunch & early bird specials.
Kildare town is small - park anywhere and you'll be within 100 yards or so of any of the places. Outlet village overlooks the motorway.