Sir,any amadment in exemption limit under saction10(10AA)(ii) - budget 2023 effect from date ?

Yes.

Leave encashment to non-government employees, at the time of retirement is partly exempt and partly taxable. 
The exemption is based on the calculation specified in Section 10(10AA)(ii). The exemption criteria limit under the section has been increased from 3 lakhs to 25 lakhs for non-government employees.  

Effective date 1st April, 2023 onwards.

Though not gone through details of finance act 2023, but as per finance bill released in February, the amendment in the section would apply from FY 2023-24, and not retrospectively.