For the data you've posted, you could do this with a wildcard Find/Replace, where:
Find = ([!^l^13])([^l^13])([0-9]@BX)
Replace = \1\2\2\3
The F/R expressions are more elaborate than they probably need to be because: (a) I don't know whether your lines are separated by newline characters (↵) or paragraph breaks (¶); and (b) I don't know whether the extra space already exists in some cases.

No code required.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]