In a manual TOC, spaces/periods may work with certain fonts and sizes, but it's very likely to stop working soon (for example if you open the document on a system where the original font is not present).
Instead, you will have to set a right-aligned tab stop with a tab leader for the page numbers on the right. Then replace the periods you are using as tab leaders with an actual tab character (inserted by pressing Tab).
For more, take a look at
http://wordfaqs.mvps.org/ManualTOC.htm.