If You are using Raid manager 6.1.1 or below the answer is NO. I am not 100 percent sure about expanding it in raid manager 6.2.2 and 6.2.1. Please check SUN documentation or check with SUN.
If You are using veritas volume manager You can always create one more LUN and configure this LUN under veritas Volume manager and expand the file system. With this procedure one need not have to destroy the LUN. Please make sure that the newly created LUN is correctly balanced for the best performance and availability. I prefer using hardware raid 5 for creating LUNs.
Sincerely,
Poorna..