To renew a CCNA with sth else than the CCNA exam, you must pass a level 642 exam (commonly BSCI, BCMSN, BCRAN or CIT, etc). Look it up on Cisco's web site.
I wouldn't recommend taking the Composite. I've done it myself and yes, the others are right, it is quite brutal...esp. when you do it to skip an exam.
An easy thing to would be to do BCMSN. It's basically all about switching. Of course, the most interesting part of CCNP (imo)is routing, but if you need to fix this thing quick, switching is the way...
I'm currently studying for BCRAN and to tell the truth I don't think the variety of subjects covered in there are easily covered within your time frame...Though your time at work must be spent troubleshooting FR and/or broadband, there is also VPN,NAT and queueing that are covered by this exam...
Of course I'm working more with switches than WAN techs, but that's my 2 cents...
M.