First, add a space after the period, and ctrl+h calls up the replacement dialog box to find the input: ([A-z])

Replace with the input:1(there is a space after1)

Select Use Wildcards in Advanced.

Click Replace All.

Then replace the extra spaces, and ctrl+h brings up the replacement dialog box. Enter two spaces for the search content and replace it with one space, and then click "Replace All" several times until you are prompted to replace 0;