From my understanding, the network does this itself. I don't believe tampering with this is necessarily beneficial for the network IMHO. Low average uptime hosts do not necessarily deserve UP status (particularly but not only if their ip addressing is highly dynamic.)

Possible misconception: Many people seem to think being an ultrapeer means you get better search results. I recall one of the original FrostWire devs & a major LW contributor saying (on this forum) that leafs actually obtain a superior search horizon than UP's. Of course that can potentially be hampered by dud or poorly performing UP's along the way, etc.
In my personal (and recent) testing on this leaf versus ultrapeer topic, I found as a leaf I was getting more search results for the same search terms than when I connected as an ultrapeer. Example: around 120 compared to around or over 200. A notable difference and this test repeated over several sessions.

Sorry this post is actually off-topic from your original thread topic.