Project Management breeds life-long learners. You always can learn from managing projects and being in a lead role within a project, no matter what industry or what level you are at.  

That is the exciting yet scary thing about projects, you must be open to new approaches and adding new tools on your belt to always strive to "increase the probability of success".  

Some example areas or subjects that a PM can focus on when planning their professional development (in no order of priority) include:
1)      Integration Management – properly coordinate project work.
2)      Scope management – ensure it is clearly identified what work will be done and what are the boundaries.
3)      Change control - enable new changes to be integrated into the plans effectively and efficiently.
4)      Time management – organize tasks to be executed in a sequential, efficient schedule.
5)      Financials management – plan, track and budget project costs and expenses.
6)      Estimation management – ability to leverage tools and techniques to attain accurate project estimates (e.g. costs, resources).
7)      Quality Management – ensure metrics and requirements are met.
8)      Resource Management – effectively utilize the resources.
9)      Information management – efficiently and effectively manage information that is collected throughout the project life cycle.
10)   Risk management – identify, assess and manage risks and other influencers.
11)   Procurement (contractor) management – ensure productive environment and relationships external to your organization.
12)   Issue management – manage issues, effectively make decisions and rapidly act.
13)   Best Practices – knowledge and understanding of global best practices in project management, tools, templates, techniques and methodologies.
14)   Technologies – ability to leverage technology and software to improve efficiency and effectiveness and process automation.
15)   Organizational design and planning– understand how businesses are structured and how plans are set for the current timeframe and well into the future.
16)   Operational Environments – what will the project work be handed off to and how will they manage and maximize it.
17)   Business acumen – professional understanding of business success factors, entrepreneurial spirit.
18)   Legal and contract Management – for the region business is undertaken.
19)   Sales Management – ability to sell another on an idea
20)   Drama/Acting – ability to alter oneself to communicate to others

The list can go on and on, a few more ones that are worth mentioning....
21)   Document control
22)   Graphing and Analysis
23)   Business Intelligence and data analytics
24)   Business Administration
25)   Marketing
26)   Safety
27)   Accounting and finance
28)   Environment
29)   Mathematics
30)   Engineering 

REMINDER:  your professional development plan is not maximized unless it is documented.  You must be responsible for your career plan of professional development and document it and keep it updated over the many years that you work.