What are your section scores? Do you feel you did not reach your normal level? Sometimes people do not get a good score in the first attempt simply because they are not used to the testing environment. If you feel there's room for your to improve, I don't think it's going to look bad for you for retaking the test.
Of course depending on your school of choice, 630 may just be good enough. You don't have to pressure yourself to reach 700. If you have good academic record and/or good working experience, or other things that would make you stand out from the others, it may be more effecient to work on the other materials.