I agree with leighanne143 it took me 4 weeks for my levels to completely go down and then another 2 to get my period. Some people I've heard its taken 11+ weeks to go down and others it went down within a matter of days. Just have your doctor to continue to take blood samples to make sure levels are dropping like they should be. If another pregnancy is suspected you'll still want them to check to make sure they are rising.
well i had 2 MC's and 2 d and c's. with the first one it took 7 weeks for my levels to go back down to zero and for me to get my pperiod again, but with my second it only took 2 weeks and i had my period again.
it varies woman by woman but they say average is like 6 weeks.