Although there are many potential treatments that will help with "lifeless" looking skin, there are none that "allow" you to get more sun exposure without creating damage of any kind.
You can easily get a Fraxel treatment and then spend 1-2 weeks out of the sun in recovery. The same goes for other forms of laser resurfacing, although the time out of the sun varies between a few days and a few weeks depending on whether you choose CO2 laser resurfacing, fractional, Erbium or some other "no downtime" lasers. Generally speaking, the best results are had with procedures that have the most downtime.
So, if you can handle taking a week or two off from the beach, you have lots of great options. If not, then you just might have to stick with the sunscreen until the laser resurfacing procedures are a higher priority. Good luck.