Didn't you keep the original Excel file? It would — most likely — mean you have to re-do the formatting, but I don't think that'd survive the round-trip anyway.
Tables are correctly exported in RTF, so you can look at them in Word … well, I got stuck there as I'm not really into Word. Perhaps copy+paste would work from that into Excel.
Here's a suggestion. Convert the tables in InDesign to plain text, with a comma inbetween the values (the Convert-to-text allows you to change it from its default Tab). Then export to plain text, and import as CVS (Comma Separated Values) into Excel.
This does work even if the text contains comma's, tabs and hard returns — you have to replace them with something “safe” first, such as [ThisWasAComma] [etc.] before converting to text.
It will definitely not work for anything else than a pure plain table — in casu, merged cells and columns will be lost or mangled beyond recognition.