You can try to update your Slot Cycle Index via EPST (more info in this thread:
http://forum.ppcgeeks.com/showthread.php?t=42730). This will increase the rate your phone will poll the cell towers for calls/text. I heard there's a slight battery decrease, but I haven't seen much difference.
Also, I read somewhere that Sprint advised people with text delays to soft reset their phones nightly, if not at least four times a week. Given the nature of WM phones, soft resetting frequently is a good habit anyway.