as Myles says… just get the same type of blade but keep them seperate for the tougher materials. one thing to note though…
Reflective, if you cut allot of it or lots of small text. its better to have a separate blade for cutting "reflective only" than any other vinyl. reflective vinyl has tiny glass beads in its vinyl build so when you consider your blade being dragged through this continually, it does blunt the blade much quicker than if its cutting regular vinyl.
a good source for various type blades is PRINT-ONE.
http://www.print1uk.com/index.php?cPath=9