I have not seen any limitations with respect to number of vlookup's allowed in a xcelsius.
Thanks for letting me know about Index and Match. Agree it is better than vlookup. I have now successfully replaced Vlookup with Index /Match. Also I could use as many Index and Match functions across multiple sheets in a XLF file.
And thanks for the sharing the blog on Index-Match to replace Vlookup.
/Arun