This might sound odd, but when winter finally goes and I put my mw and hw rugs away, how do I know of they'll need re proofing for next winter? They were new this year and hoping they'll still fit my youngster next winter!
throw a rug over a silage bale leave a hosepipe running over it for an hour ,turn it over to see how waterproof it is .Alternatively go to any camping shop ,or ebay and buy a tin of tent [canvas] waterproofer [£ 15 for 2.5 litre or cheaper ] brush on or spray on with an old kitchen cleaner sprayer ,works a treat and is way cheaper than the rug cleaning people re proofing it .
If they are new then chances are they shouldnt need re-proofing atall.. if you thought they needed re-proofing then they would need washing first with horse rug wash products to get out all the grime. If they arent greasy inside then personally I wouldnt bother.
What brand are they? Good quality rugs shouldnt be leaking anyway after 1 winter.
Then unless they are really scruffy or greasy inside then I would put them away until next year. If you decide to have them cleaned then they shouldnt need re-proofing after a first wash, probably after any subsequent washes. A lot depends too on the amount of wear they have, eg living out or not.
(I tend to wash and re-proof mine after each season but then I can as its what I do as my own business)
I only reproof when they leak too. I have just put my Rambo (which I have used a lot) in to be reproofed for the first time and I have had it for nearly 10 years. I have never had any of the others reproofed yet and have had them ages.
I only tend to clean turnouts every other year unless they are really bad, I find it makes them leak, and I only re proof if they leak and most dont if not cleaned to much I find.