Definitely clean the lenses first before trying anything else. You will be surprised just how much they get covered in much. Did mine a while ago with 't-cut' and the stuff that came off was unbelievable!! Did it 3 times, and the lenses came up as new!! (I tend to do them every 3 months or so now, routinely)
Once you have cleaned them, them think if you need new bulbs or not. I purchased some 'Osram Nightbreaker plus' bulbs from E-bay, and replaced both the dipped beam (H7) and the main beam (H1) for around £25 for the lot (2 packs of 2 bulbs) and again, the difference is amazing along with the cleaned lenses.
Do the cleaning first, that may well be enough, then decide if you need new bulbs..