Our office receives many requests on how to convert a PERM petition from EB-3 to EB-2, however in light of the recent movement for China on the visa bulletin we are now receiving more requests on how to convert from EB-2 to EB-3.
Chinese nationals who have either a pending or an approved EB-2 I-140 petition are becoming interested in learning how to convert their EB-2 petition to EB3 petition if possible.
New EB-3 PERM is NOT Required:
The 2007 Neufeld Memo made exceptions to file the subsequent or amended I-140 petition with a copy of a labor certification that is expired the time the amended or duplicated Form I-140 is filed, if the original approved labor certification was filed in support of previously filed petition during the labor certification’s validity period.
A new perm will not be required “in the instances where the amended petition is requesting a different visa classification than the visa classification requested in the previously filed petition, or when the previously filed Form I-140 petition has been determined to have been lost by USCIS or DOS. 
You can retain the previous priority date:
According to 8 C.F.R. § 204.5(e), a subsequent EB-1, EB-2 or EB-3 petition is entitled to earliest priority date, unless the prior petition is revoked due to fraud.
This means that if the beneficiary gets a new approval under EB-3 visa category he/she should be able to port the previous priority date form his/her previously approved EB-2 petition.
How does this affect my I-485 application?
If the beneficiary has a pending I-485 Adjustment of Status filed based on an approved EB-2 I-140, the adjustment of status application should be transferred to the subsequently filed EB-3 petition provided that the priority date is current for EB-3 and the applicant continues to be eligible for adjustment of status. 
If the beneficiary has not filed I-485 Adjustment of Status as the priority date was not current, filing EB-3 petition would allow them to file I-485 Adjustment of Status application concurrently.
Checklist on filing the subsequent I-140 EB-3 petition: 
- Be sure the beneficiary qualifies under the new category;
- Do not revoke or withdraw the initial I-140 petition;
- Indicate on the cover letter that you are filing a subsequent I-140 petition in accordance with 8 CFR §204.5(e), indicate the classification you are seeking, and explain that an original labor certification is not attached because it was filed with a previous I-140 petition;
- Include the PERM number on page 3 of the I-140, check the appropriate box noting that the original labor certification was previously filed, and include the previous I-140 receipt number in an attached explanation;
- Include all evidence of the beneficiary’s qualifications for the position offered, as well as documentation of the employer’s continuing ability to pay the prevailing wage;
- Include a copy of the EB-2 I-140 approval notice, which will contain a priority date and file number;
- Provide a copy of the approved labor certification.
 June 1, 2007 Neufeld Memorandum, “Interim Guidance Regarding the Impact of the Department of Labor’s (DOL) final rule, Labor Certification for the Permanent Employment of Aliens in the United States; Reducing the Incentives and Opportunities for Fraud and Abuse and Enhancing Program Integrity, on Determining Labor Certification Validity and the Prohibition of Labor Certification Substitution Requests”, published on AILA InfoNet at Doc. No. 07062172.
 May 9, 2000 Pearson Memorandum, “Transferring Section 245 Adjustment Application to New or Subsequent Family or Employment-Based Immigrant Visa Petitions” (may 9, 2000), published on AILA InfoNet at Doc. No. 00062110.
 “Multiple I-140s, Priority Date Retention, and the 2013 China EB-2/EB3 Anomaly”, published on AILA InfoNet Doc. No. 13120548. (Posted 12/16/13).