you have to be careful with changing the productversion property of
your setup project within the VS environment as this will change your
packagecode and productcode, which results in the installer recognizing
your package as a major upgrade.

to do minor updates, you want to increment the project's version
property, accept the changes to the code, and set the productcode
property back to the original product you were updating. this way, when
you run the resulting package, it will recognize that the product is
already installed, but it's a different package, hence comparing the
updates needed. to install this package, you can do the following to
force a reinstall.

msiexec /I mypackage.msi REINSTALL=ALL REINSTALLMODE=VOMUS

this way, the "repair" option is not an uninstall/reinstall, but a
minor upgrade taking place.

good luck :)