Put the try/catch in a method then recall the method from the catch part?
sub1
dim isOK boolean = false
while not isOK then
isOK = funct1()
end While
end sub1
funct1() as boolean
try
'bit that may fall over
return true
catch ex as exception
return false
end try
end func1
sub1 button_click()
if not isRubishData(txt1.text) then
'do processing
else
'Throw message at user
end if
end sub
function isRubishData(inData) as boolean
return whatever
end function