Presuming that your Visa is still current and valid then you are able to use it without any notification.
In respect to it still being valid, the most obvious thing to check is the expiry date on the visa itself. You will not be allowed enter the US after the expiry date on the visa. Normally B1/B2 visas are issued for 10 years so you should be fine, however they can be issued for shorter periods (even as low as 1 year or less).
You should also check the visa to make sure there that if there are any "Annotations" that they are still current. The annotations are basically additional conditions for the visa, and could range from anything like "Single entry only" or some other limitation for what the visa can be used for. Normally a B1/B2 will not have any annotations.
Finally, you should be sure that none of the answers that you gave when you applied for your visa have changed significantly. eg, if you have been arrested since your visa application, then the visa is most likely invalid and you should contact the US consulate to find out how to proceed.
Otherwise, you're good to go!