Don't beat yourself up about it.....Western Civ I was by far one of the most difficult exams for me, just because of the sheer volume of information (and I was also homeschooled). When you retake it, I strongly suggest reading your highschool world history book again, getting the REA CLEP Western Civ. guide Amazon.com: CLEP Western Civilization I w/ CD-ROM (REA) -- Ancient Near East to 1648: Ancient Near East to 1648 (REA Test Preps): Books: Robert M Ziomkowski,Larissa Juliet Taylor and doing its practice tests several times (and reading the answers) and doing IC over and over. Plan to spend about 2-3 weeks of extensive study on it.

Also, do you have the general book of CLEP practice tests? Amazon.com: CLEP Official Study Guide: 18th Edition (Clep Official Study Guide): Books: The College Board I always take the practice test a day or two before taking the real thing. Personally, if I didn't get over half of the questions right, I would reschedule the test. I can't recommend this book highly enough--it gives you some idea of what stuff will be covered and allows you to gauge your readiness.

Better luck next time!