Your CRB status will be updated from negative to positive after you have completed repaying the loan and the listing institution has forwarded your name to CRB for de-listing.
If your listing institution has not submitted a notification to indicate that you have repaid your loan, then you should contact them.
NOTE: Your name will still be remain in CRB after repaying your loan for 5 to 6 years. Your worry should be if you are listed negatively.