V-shape vein on my forehead. Tried sclerotherapy and vascular laser with no results, would dermal fillers work? (photos)

I would retreat your forehead veins with sclerotherapy.  The success of forehead  veins resolution depends on many factors but, most importantly, the experience of the doctor treating these veins.  Topical laser has no role here.  I usually use a butterfly and  STS with excellent results.  In addition compression during the procedure and following are also very important.  Sometimes I also make microincisions or punctures at the hairline to adequately drain the vein.

Hello,
The sclerotherapy solution used was probably not strong enough, and laser has no role in this kind of veins. It is a dangerous area that requires a vascular physician trained for this technique. 
A couple of sessions may be necessary if the Dr uses a correct protocol. A vein avulsion is also possible but there is increased risk of scar and more downtime. 

In our office we use a combination of foam sclerotherapy and phlebectomy (a minimally invasive removal performed using local anesthetic and a 1 mm incision at the hairline). Regular sclerotherapy is probably not potent enough and I have not seen a laser with sufficient energy to treat a vein of this caliber. Whomever you go to, make sure they have done it before as the drainage from this area can have connections to drainage to the eyes or brain and may also communicate with the blood supply of the scalp (which, if injured, could lead to the death of the skin in this area). Good luck.