How much more calcium should I take while pregnant?

Yes, supplement. In addition to a well-balanced diet, calcium may be supplemented. 600-1200mg/day of calcium is appropriate. In addition, many women are deficient in vitamin d. 200-400iu of vitamin d, in addition to prenatal vitamin supplementation, should suffice. Your obstetrician may screen for vitamin d deficiency by doing certain bloodwork. There are many brands that combine calcium and vitamin d together.
No more than usual. The institute of medicine of the national academy of sciences recommends intake of 1300 mg of calcium daily for girls ages 14 to 18 and 1000 mg per day for women ages 19 to 50. This recommendation is the same during pregnancy and lactation.