Dial *228 to reset your signal.If that doesn't help,dial 611 & talk to a CRICKET REP & explain your situation to them.They actually helped me out when I was having signal issues.
If those two things do not help,you're probably in a fringe area that has a weak signal.Take a look @ the coverage map @ mycricket.com & see if you're bordering a coverage area.
One more thing,if you're using a task killer &/or a battery saving app,ditch them & watch your signal improve.
Edit:If you've used more than 1GB of 3G data during your current billing cycle,you're probably being throttled,meaning that your data speeds will be slower (1x) until your next billing cycle starts.