Most of the preventive measures for bird strikes are at/around the airport but what are some of the ways that can be used to prevent bird strikes on the plane as it is climbing or in flight?
Airports engage in a number of strategies to reduce the number of birds nearby that might cause strikes. This has been addressed in a previous question: What are the ways to keep the birds away from airfields?
Avian Radar also exists:
Avian radar is an important tool for aiding in bird strike mitigation as part of overall safety management systems at civilian and military airfields. Properly designed and equipped avian radars can track thousands of birds simultaneously in real-time, night and day, through 360° of coverage, out to ranges of 10 km and beyond for flocks, updating every target's position (longitude, latitude, altitude), speed, heading, and size every 2–3 seconds. Data from these systems can be used to generate information products ranging from real-time threat alerts to historical analyses of bird activity patterns in both time and space.
Installations include civil applications at New York/John F Kennedy International Airport, Chicago/O'Hare International Airport and Seattle-Tacoma although the majority of both deployment and development activity is still focussed (sic) on military air movements.
MERLIN Avian Radar System technology...is used...to detect and monitor hazardous bird activity on and around airfields for bird-aircraft strike hazard management.
In my Cessna 172 my eyes are the only advance warning system available. I've used them a couple of times to avoid large birds, and not necessarily on approach. I also know of several bird strikes in small planes that are just good stories after the clean up at the airport. On the other hand, I also have heard of windscreens being shattered but the pilot still being able to maintain control and land the aircraft normally.
I suspect your question was written with airliners in mind, but bird strikes are not uncommon in small airplanes, and the results are mostly unremarkable.
See and avoid. Avoid not always possible, especially when moving fast and you don't see it/them coming, or are just not that maneuverable.