Zeiss made some Proxar lenses for the standard 45mm & 50mm Tessars. They are often found as a set in their plastic case which features a depth of field calculator dial on the reverse. Usually the set is infinity at 1 metre; 50cm; 30 cm & 20cm. They can be readily purchased on ebay, for example, either individually or as a set. Some retailers ask for $50 plus however with a little searching and patience they can be found for $30 or less, maybe much less at markets or garage sales. Here's a set I
plucked off a quick ebay search that seem reasonably priced, I know nothing of the seller though.
A 1:1 Macro Pro Tessar was also made in early and late versions for the Contaflex III and later unit focus models. This is one of a couple of Pro Tessars I don't own yet however it is said to be very sharp. It generally lists for USD $100 or more.
A close up lens was also made for the 85mm Pro Tessar. It can be used with either the f/4 or f/3.2 labelled lenses. It brings infinity back to 1.3 metres, useful for head shots or very tight head and shoulder portraits. The 85mm Pro Tessar has a substantially shorter minimum focus distance than the 115mm and is arguably the most useful additional lens although I should also mention I've found the 35mm f/3.2 to be quite sharp.
But if you are for the time being limited to the Contaflex II, this, like the original, has the front cell focus 45mm f/2.8 Tessar. This does not accept interchangeable Pro Tessar lenses except for the Teleskop additional lens (although I am not sure if you can attach a Monocular to a I or II without checking, sorry).
I do not own a Teleskop yet but they are readily sourced online from USD $50-100 usually, sometimes more or less of course. An accessory bracket is needed to attach the Teleskop, some sellers do sell these separately, if you purchase a lens without the bracket make sure it is very cheap as you'll need to procure a bracket to attach it. I have never tried the Teleskop but Mike Elek (ZeissFan on RFF) says it is very good. See his Contaflex page:
http://elekm.net/pages/cameras/contaflex_1.htm
You can get some idea of what the Teleskop looks like from the images on
this listing (again, I know absolutely nothing about the seller, I entered "Contaflex Teleskop" into ebays search engine and this was the first result). Having said that, with the original box and front and rear caps all in nice nick it looks rather appealing, if I was cashed up this week I might have bought it...
Cheers,
Brett