If your plans are on Paper and you need an exact copy in CAD, the best way to convert them to CAD is to work from a scanned copy.
These days, plans converted to PDF or JPG can easily be sent out for bid, reviewed and converted to CAD. Digital copies of your drawings can be inserted into the CAD and then traced.
If your plans are old and damaged, take them to a printer who specializes in working with Architectural and Engineering Graphics. If your plans are in good condition, any copy center, such as FedEX, can convert them for you.