I took 2 years of Arabic in college and I felt that our vocab base was very small at the end. I'm also pretty sure SOLT and DLI will be more difficult than my classes so I started to look around for other resources and found one that might help you or anyone else on the Arabic track.
This is a blog for a guy who deals mainly with military students in DLI. He is well versed in DLPT 5 and understands the issues involved with learning Arabic quickly. The info can be a little dated but there are lots of useful tips that deal with the DLPT and learning Arabic. The guy is also a native speaker so that will help as well.
http://acedlptarabic.blogspot.com/
The real helpful thing is that he has a book available that is geared specifically to taking the DLPT. It has 400 passages to read along with CD support which is easy to put on an iPod or similar device.
Site:
http://www.globallanguagesystems.com/
Here are the bullet points about the book:
• Over 400 challenging passages, questions, and audio files by a native speaker of Arabic simulating the actual DLPT format for real practice testing experience.
• Live material from various open media sources covering all DLPT content objectives including economics, politics, science, technology, geography, culture, social, military, and security.
• Comprehensive exposure to critical terminology and vocabulary, both familiar and unfamiliar, in various contexts, to increase your overall vocabulary and to improve your ability to infer and deduce meaning.
• Material of varying levels of complexity, including Arabic and foreign names of people and places, to challenge your listening and reading comprehension.
You can get the book on Amazon as well:
http://www.amazon.com/Ace-My-Languag.../dp/0976840413