How to maintain DWR on PacLite on long trip

1. while on the trip wash only in hot water – no soap or detergent
2. take a small bottle of NikWax wash-in DWR with you (IF you are sure you can find a commercial or hotel drier). Wash it by hand 1st then soak in NikWax & water and agitate by hand, shake off excess liquid and put in a drier at medium heat. CHECK after 5 mins. to see that the drier is the correct temp, not too hot or not merely barely warm.

If you can find a laundromat with a heat adjustment on a dryer, just put it in at low heat for about 30 mins. Otherwise, I wouldn't go over five mins. Some laundromat dryers get very hot. The permanent press setting on my home dryer works great at 30 mins. on low heat.

My Patagonia Specter went almost a decade before needing the dryer. A jacket that won't last a year without more than light heat to refresh the DWR may not be the best quality around. Am assuming there are laundromats in S.A., but have never been there.

Have never had to wash my rain jacket, used only for rainy backpacking in the Rockies and NE USA, but given the climate in S.A., and that you may be using the jacket in cities and towns, you may have to wash it to get stains and the perspiration oils out.
Suggest bringing a bottle of Atsko Sportwash to use. Just a capful per wash. If all the above leaves you without good DWR, you will have to follow Eric's suggestion.
If that doesn't work, the ReviveX spray on DWR might help.