Set %var as a global variable when it gets declared (e.g. $var = %var;) and use this loop to continue checking for it until it exists.
function checkVar()
{
if($var !$= "")
{
$var2 = getWord($var,0);
}
else
{
$var2sched = schedule(100,0,"checkVar");
}
}
You can use cancel($var2sched); if it never finds a result for $var.