AFAIK, there is no native option to update the conf file directly. From many activities in Splunk Web, the conf files will get update, so what all conf files/entries you're looking to update from Splunk Web?
If you're in 6.3 OR above, you can update props.conf from Settings->Source types (for sourcetype definitation) OR Settings-> Fields (for field extractionos/transformation).
Inputs.conf can be update (indirectly) from UI Settings->Data Inputs, for regular properties. The advanced properties should be updated only by Splunk Administrators who have in-depth knowledge about those properties, hence they are not exposed via UI.
Thanks for your information, but i not found any option which can be update my props.conf file ,through which i will use data masking regex expression.