Yes, aliens always have the option to redeploy within the destination area every time they move. It has also been stated that aliens will always redeploy to base an agent if possible.
In the rule book, since I was looking at this very rule today, it says they will ONLY redeploy to come adjacent to an agent, it doesn't say anything about redeploying to gain LOS.
Which makes sense to me anyway. If they didn't have LOS, how would the alien know that moving an extra hex would give them LOS? Unlike moving adjacent where the alien WOULD know an extra hex would engage the target.