We had... (counting in my head...) three major rounds of testing in... ummm... six years.
If the last round was really comprehensive but it's been a year or two, you can at least get a second opinion - they will get the test results (the detailed ones you don't get to see) and re-interpret, and sometimes find what the first one missed.
If the last round wasn't comprehensive... go for it. If you don't have all the answers, then you need to keep asking.
And yes, if your other child has significant challenges, get that one started too.
As far as the Risperidone goes, it usually takes a couple of weeks to build up in the system. On a really sensitive child, you might see some effect after a week.
