Sclerotherapy is a process and usually requires around 3 sessions and sometimes more depending on the amount of veins. There is also maintenance required over time. From the pictures posted it looks as if you have had a response to treatment. I usually wait 6 weeks between treatments as veins continue to dissolve over this period. I would recommend that you continue with your sclerotherapy.
Sclerotherapy works by causing an inflammation of the lining of the blood vessel. Compression then makes the two sides stick together and scar thus eliminating the spider vein. A spider vein is out of the circulation and does not provide blood to the skin, they just look bad. Sclerotherapy can be technically challenging and there are a variety of agents used. I generally use hypertonic saline. I have found that approximately 85% of patients will respond to treatment. I aways do a test area first to see if it is going to be effective for a patient.
You need another session. Success depends on the type of sclerosant used, the technique (foam or traditional) and post procedure care.
As cosmetic procedures go, sclerotherapy is not expensive. Expect to have 2-3 more sessions or perhaps have some of those telangiectasias lasered - topical laser.
If you don't get them treated appropriately or completely, they will proliferate and you will have to spend more money.
Also spend some money and use some topical products to reduce the hyperpigmentation (brown discoloration). We recommend VenoQuin and VenoLucent creams (less than 100 dolars) and use them for 3 motnhs on the injected areas. Avoid tanning. Wear compression stockings over the injected areas to increase success rate.