even after miscarriage
for some days pregnancy
test can come positive as the HCG levels which are elevated could be still there in the blood and will take sometime for the value to become zero,
and that will depend on pre miscarriage levels,
so you better wait for two more weeks then repeat the blood test
if the the positive HCG levels are because of previous abortion
they will come down,
if there is chance of pregnancy again then you will see positive test again with elevated levels of HCG.